Problem:


Score : 300 points

Problem Statement

There is an integer sequence A of length N whose values are unknown.

Given is an integer sequence B of length N-1 which is known to satisfy the following:

 B_i \geq \max(A_i, A_{i+1}) 

Find the maximum possible sum of the elements of A.

Constraints

All values in input are integers.

2 \leq N \leq 100

0 \leq B_i \leq 10^5

Input

Input is given from Standard Input in the following format:

N
B_1 B_2 ... B_{N-1}

Output

Print the maximum possible sum of the elements of A.

Sample Input 1

3
2 5

Sample Output 1

9

A can be, for example, ( 2 , 1 , 5 ), ( -1 , -2 , -3 ), or ( 2 , 2 , 5 ). Among those candidates, A = ( 2 , 2 , 5 ) has the maximum possible sum.

Sample Input 2

2
3

Sample Output 2

6

Sample Input 3

6
0 153 10 10 23

Sample Output 3

53



Sample input:
3
2 5


Sample output:
9

Submission status: Accepted

Solution code:
def main(sample_file = ''):

    """ convenient functions
    # for i, a in enumerate(iterable)
    # q, mod = divmod(a, b)
    # divmod(x, y) returns the tuple (x//y, x%y)
    # Higher-order function: reduce(operator.mul, xyz_count, 1)
    # manage median(s) using two heapq https://atcoder.jp/contests/abc127/tasks/abc127_f
    """

    """convenient decorator
    # @functools.lru_cache():
    # to facilitate use of recursive function
        # ex:
        # from functools import lru_cache
        # import sys
        # sys.setrecursionlimit(10**9)
        # @lru_cache(maxsize=None)
        # def fib(n):
        #     if n < 2:
        #         return n
        #     return fib(n-1) + fib(n-2)
        # print(fib(1000))
    """
    
    # import numpy as np
    import sys
    sys.setrecursionlimit(10**7)
    from itertools import accumulate, combinations, permutations, product # https://docs.python.org/ja/3/library/itertools.html
    # accumulate() returns iterator! to get list: list(accumulate())
    from math import factorial, ceil, floor, sqrt
    def factorize(n):
        """return the factors of the Arg and count of each factor
        
        Args:
            n (long): number to be resolved into factors
        
        Returns:
            list of tuples: factorize(220) returns [(2, 2), (5, 1), (11, 1)]
        """
        fct = []  # prime factor
        b, e = 2, 0  # base, exponent
        while b * b <= n:
            while n % b == 0:
                n = n // b
                e = e + 1
            if e > 0:
                fct.append((b, e))
            b, e = b + 1, 0
        if n > 1:
            fct.append((n, 1))
        return fct
    def combinations_count(n, r):
        """Return the number of selecting r pieces of items from n kinds of items.
        
        Args:
            n (long): number
            r (long): number
        
        Raises:
            Exception: not defined when n or r is negative
        
        Returns:
            long: number
        """
        # TODO: How should I do when n - r is negative?
        if n < 0 or r < 0:
            raise Exception('combinations_count(n, r) not defined when n or r is negative')
        if n - r < r: r = n - r
        if r < 0: return 0
        if r == 0: return 1
        if r == 1: return n
        numerator = [n - r + k + 1 for k in range(r)]
        denominator = [k + 1 for k in range(r)]
        for p in range(2,r+1):
            pivot = denominator[p - 1]
            if pivot > 1:
                offset = (n - r) % p
                for k in range(p-1,r,p):
                    numerator[k - offset] /= pivot
                    denominator[k] /= pivot
        result = 1
        for k in range(r):
            if numerator[k] > 1:
                result *= int(numerator[k])
        return result
    def combinations_with_replacement_count(n, r):
        """Return the number of selecting r pieces of items from n kinds of items allowing individual elements to be repeated more than once.
        
        Args:
            n (long): number
            r (long): number
        
        Raises:
            Exception: not defined when n or r is negative
        
        Returns:
            long: number
        """
        if n < 0 or r < 0:
            raise Exception('combinations_with_replacement_count(n, r) not defined when n or r is negative')
        elif n == 0:
            return 1
        else:
            return combinations_count(n + r - 1, r)
    from bisect import bisect_left, bisect_right
    from collections import deque, Counter, defaultdict # https://docs.python.org/ja/3/library/collections.html#collections.deque
    from heapq import heapify, heappop, heappush, heappushpop, heapreplace,nlargest,nsmallest # https://docs.python.org/ja/3/library/heapq.html
    from copy import deepcopy, copy # https://docs.python.org/ja/3/library/copy.html
    import operator
    from operator import itemgetter #sort 
    # ex1: List.sort(key=itemgetter(1))
    # ex2: sorted(tuples, key=itemgetter(1,2))
    from functools import reduce, lru_cache
    def chmin(x, y):
        """change minimum
        if x > y, x = y and return (x, True).
        convenient when solving problems of dp[i]
        
        Args:
            x (long): current minimum value
            y (long): potential minimum value
        
        Returns:
            (x, bool): (x, True) when updated, else (x, False)
        """
        if x > y:
            x = y
            return (x, True)
        else:
            return (x, False)
    def chmax(x, y):
        """change maximum
        if x < y, x = y and return (x, True).
        convenient when solving problems of dp[i]
        
        Args:
            x (long): current maximum value
            y (long): potential maximum value
        
        Returns:
            (x, bool): (x, True) when updated, else (x, False)
        """
        if x < y:
            x = y
            return (x, True)
        else:
            return (x, False)

    from fractions import gcd # Deprecated since version 3.5: Use math.gcd() instead.
    def gcds(numbers):
        return reduce(gcd, numbers)
    def lcm(x, y):
        return (x * y) // gcd(x, y)
    def lcms(numbers):
        return reduce(lcm, numbers, 1)
    def make_divisors(n, reversed=False):
        """create list of divisors
        
        Args:
            number (int): number from which list of divisors is created
            reversed (bool, optional): ascending order if False. Defaults to False.
        
        Returns:
            list: list of divisors
        """
        divisors = set()
        for i in range(1, int(n**0.5)+1):
            if n % i == 0:
                divisors.add(i)
                divisors.add(n//i)
        return sorted(list(divisors),reverse=reversed)
    
    # first create factorial_list
    # fac_list = mod_factorial_list(n)
    INF = 10 ** 18
    MOD = 10 ** 9 + 7
    modpow = lambda a, n, p = MOD: pow(a, n, p) # Recursive function in python is slow!
    def modinv(a, p = MOD):
        # evaluate reciprocal using Fermat's little theorem:
        # a**(p-1) is identical to 1 (mod p) when a and p is coprime
        return modpow(a, p-2, p)
    def modinv_list(n, p = MOD):
        if n <= 1:
            return [0,1][:n+1]
        else:
            inv_t = [0,1]
            for i in range(2, n+1):
                inv_t += [inv_t[p % i] * (p - int(p / i)) % p]
            return inv_t
    def modfactorial_list(n, p = MOD):
        if n == 0:
            return [1]
        else:
            l = [0] * (n+1)
            tmp = 1
            for i in range(1, n+1):
                tmp = tmp * i % p
                l[i] = tmp
            return l
    def modcomb(n, k, fac_list = [], p = MOD):
        # fac_list = modfactorial_list(100)
        # print(modcomb(100, 5, modfactorial_list(100)))
        from math import factorial
        if n < 0 or k < 0 or n < k: return 0
        if n == 0 or k == 0: return 1
        if len(fac_list) <= n:
            a = factorial(n) % p
            b = factorial(k) % p
            c = factorial(n-k) % p
        else:
            a = fac_list[n]
            b = fac_list[k]
            c = fac_list[n-k]
        return (a * modpow(b, p-2, p) * modpow(c, p-2, p)) % p
    def modadd(a, b, p = MOD):
        return (a + b) % MOD
    def modsub(a, b, p = MOD):
        return (a - b) % p
    def modmul(a, b, p = MOD):
        return ((a % p) * (b % p)) % p
    def moddiv(a, b, p = MOD):
        return modmul(a, modpow(b, p-2, p))

    class UnionFindTree:
        """union find tree class
        TODO: fix this description...
        how to use (example):
        >>  uf = UnionFindTree(N) 
        >>  if uf.find_root(a) == uf.find_root(b):
        >>      do something
        >>  else:
        >>      do something
        >>      uf.unite(a, b)
        """
        def __init__(self, N):
            self.root = [-1] * (N+1)
            self.rank   = [0]  * (N+1)
            self.connected_num = [1] * (N+1)
    
        def find_root(self,x):
            root = self.root
            while root[x] != -1:
                x = root[x]
            return x
    
        def unite(self,x,y):
            root = self.root
            rank = self.rank
            connected_num = self.connected_num
            find_root = self.find_root
    
            rx = find_root(x)
            ry = find_root(y)
            if rx != ry:
                if rank[rx] < rank[ry]:
                    root[rx] = ry
                    rx,ry = ry,rx
                else:
                    if rank[rx] == rank[ry]:
                        rank[rx] += 1
                    root[ry] = rx       
                connected_num[rx] += connected_num[ry]

    # Graph: https://en.wikipedia.org/wiki/Directed_graph
    # Bellman-Ford: O(|V||E|). Use this if there exists an edge with negative length in the graph
    # After N steps, the shortest path has converded if there doesn't exist an cycle of edges with negative
    # Watch out: d[N] == d[2*N] doesn't necessarily mean the graph doesn't have negative cycle
    # ref: https://www.youtube.com/watch?v=1Z6ofKN03_Y

    def BellmanFord(N, M, ABC, vertex_start, vertex_end, value_if_inf = -1, find_shortest = False):
        """to calculate furthest or shortest length between vertex_start and vertex_end using BellmanFord algorithm
        
        Args:
            N (int): number of vertices
            M (int): number of edges
            ABC (list): [(ai, bi, ci) for _ in range(N)] where i-th edge is directed from vertex ai to vertex bi and the length is ci 
            vertex_start (int): start vertex. usually use 0.
            vertex_end (int): end vertex. usually use N-1.
            value_if_inf (int or string as you like, optional): value you want when the furthest (or shortest) distance is infinite (or -infinite). Defaults to -1.
            find_shortest (bool, optional): choose False to find furthest path. Defaults to False.
        
        Returns:
            int or string: normally int (but can be str if you set value_if_inf to str)
            
        Example:
                N, M, P = R()
                ABC = [R() for _ in range(M)]
                ABC = [(a-1, b-1, c-P) for a, b, c in ABC]
                print(BellmanFord(N, M, ABC, 0, N-1, value_if_inf = 'inf'))

        """

        def make_reachable_list(N, M, ABC, vertex_start, vertex_end):
            reachable_to_direct = defaultdict(list)
            reachable_from_direct = defaultdict(list)
            reachable_from_start = [False] * N
            reachable_to_end = [False] * N
            reachable_from_start[vertex_start] = True
            reachable_to_end[vertex_end] = True
            reachable_from_both_sides = [False] * N
            dfs_from_start = []
            dfs_to_end = []
            for a, b, c in ABC:
                reachable_to_direct[a].append(b)
                reachable_from_direct[b].append(a)
                if a == vertex_start:
                    dfs_from_start.append(b)
                    reachable_from_start[b] = True
                if b == vertex_end:
                    dfs_to_end.append(a)
                    reachable_to_end[a] = True
            while dfs_from_start:
                v = dfs_from_start.pop()
                for i in reachable_to_direct[v]:
                    if not reachable_from_start[i]:
                        reachable_from_start[i] = True
                        dfs_from_start.append(i)
            while dfs_to_end:
                v = dfs_to_end.pop()
                for i in reachable_from_direct[v]:
                    if not reachable_to_end[i]:
                        reachable_to_end[i] = True
                        dfs_to_end.append(i)
            for i in range(N):
                reachable_from_both_sides[i] = reachable_from_start[i] and reachable_to_end[i]
            return reachable_from_both_sides
        
        reachable_from_both_sides = make_reachable_list(N, M, ABC, vertex_start, vertex_end)
        
        if find_shortest:
            dist = [INF for i in range(N)]
        else:
            dist = [-INF for i in range(N)]
        
        dist[vertex_start] = 0
        for i in range(N):
            updated = False
            for a, b, c in ABC:
                if not reachable_from_both_sides[a]:
                    continue
                elif find_shortest:
                    update_condition = dist[a] + c < dist[b]
                else:
                    update_condition = dist[a] + c > dist[b]
                if dist[a] != INF and update_condition:
                    dist[b] = dist[a] + c
                    updated = True
                    if i == N-1:
                        return value_if_inf
            if not updated:
                break
        return dist[vertex_end]

    """ initialize variables and set inputs
    # initialize variables
        # to initialize list, use [0] * n
        # to initialize two dimentional array, use [[0] * N for _ in range(N)]
    # set inputs
        # put inputs between specific values (almost as quickly)
        # ex) S = [-INF] + [int(r()) for _ in range(A)] + [INF]
        # open(0).read() is sometimes useful:
        # ex) n, m, *x = map(int, open(0).read().split())
        #     min(x[::2]) - max(x[1::2])
        # ex2) *x, = map(int, open(0).read().split())
        #     don't forget to add comma after *x if only one variable is used
    # preprocessing
        # transpose = [x for x in zip(*data)]
        # ex) [[1, 2, 3], [4, 5, 6], [7, 8, 9]] => [(1, 4, 7), (2, 5, 8), (3, 6, 9)]
        # flat = [flatten for inner in data for flatten in inner]
        # ex) [[1, 2, 3], [4, 5, 6], [7, 8, 9]] => [1, 2, 3, 4, 5, 6, 7, 8, 9]
    # calculate and output
        # output pattern
        # ex1) print(*l) => when l = [2, 5, 6], printed 2 5 6
    """

    # functions to read input
    r = lambda: sys.stdin.readline().strip()
    r_int = lambda: int(r())
    R = lambda: list(map(int, r().split()))
    Rmap = lambda: map(int, r().split())
    Rfloat = lambda: list(map(float, r().split()))
    Rtuple = lambda: tuple(map(int, r().split()))

    """ how to treat input
    # single int: int(r())
    # single string: r()
    # single float: float(r())
    # line int: R()
    # line string: r().split()
    # line (str, int, int): [j if i == 0 else int(j) for i, j in enumerate(r().split())]
    # lines int: [R() for _ in range(n)]
    """

    # for test
    if sample_file:
        sys.stdin = open(sample_file)
        
    # ----------------------------------
    # main

    N = r_int()
    B = R()
    A = [0] * N
    for i in range(1, N-1):
        A[i] = min(B[i], B[i-1])
    A[0] = B[0]
    A[N-1] = B[N-2]
    print(sum(A))
    
    # to finish code, use return instead of exit()
    # end of main
    # ----------------------------------

    """memo: how to use defaultdict of list
    # initialize
    Dic = defaultdict(list)
    # append / extend
    Dic[x].append(y)
    # three methods for loop: keys(), values(), items()
    for k, v in Dic.items():
    """
    
    """memo: how to solve binary problems
    # to make binary digits text
    >>> a = 5
    >>> bin_str_a = format(a, '#06b')
    >>> print(bin_str_a)
    0b0101 # first 2 strings (='0b') indicates it is binary
    """
    
    """memo: how to solve the problem
    creating simple test/answer
    greed
    simple dp
    graph
    """

if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
n = int(input())
b = [int(x) for x in input().split()]
ans = 0
for i in range(n-2):
    ans += min([b[i], b[i+1]])
ans += b[0]
ans += b[-1]
print(ans)

Submission status: Accepted

Solution code:
N=int(input())
A=list(map(int,input().split()))
count=A[0]+A[N-2]
for i in range(1,N-1):
    count+=min(A[i-1],A[i])
print(count)

Submission status: Accepted

Solution code:
N = int(input())
A = [100000] * N
B = list(map(int,input().split()))

for i in range(N-1):
    A[i] = min([A[i],B[i]])
    A[i+1] = min([A[i+1],B[i]])

print(sum(A))

Submission status: Accepted

Solution code:
N=int(input())
ls=[int(s) for s in input().split()]
sum=ls[0]+ls[N-2]
for i in range(N-2):
  sum+=min([ls[i],ls[i+1]])

print(sum)

Submission status: Accepted

Solution code:
N = int(input())
B = list(map(int,input().split()))
A = [0 for i in range(N)]
A[0] = B[0]
for i in range(1,N-1):
    A[i] = min(B[i-1], B[i])
A[N-1] = B[N-2]
print(sum(A))

Submission status: Accepted

Solution code:

import sys
def input():
	return sys.stdin.readline().strip()

N = int(input())
B = list(map(int, input().split()))

total = B[0] + B[-1]
for i in range(1, N - 1):
	total += min(B[i - 1], B[i])

print(total)

Submission status: Accepted

Solution code:
import sys
sys.setrecursionlimit(1000000000)
ii = lambda: int(input())
mis = lambda: map(int, input().split())
lmis = lambda: list(mis())

def main():
    N = ii()
    B = lmis()
    B = [B[0]] + B + [B[-1]]
    ans = 0
    for i in range(N):
        ans += min(B[i], B[i+1])
    
    print(ans)

main()

Submission status: Accepted

Solution code:
def resolve():
    N=int(input())
    B=list(map(int,input().split()))
    ans=B[0]
    for i in range(1,N-1):
        #print(min(B[i-1],B[i]),B[i-1],B[i])
        ans+=min(B[i-1],B[i])
    print(ans+B[-1])
resolve()

Submission status: Accepted

Solution code:
N = int(input())
B = list(map(int,input().split()))

ans = 0
for i in range(N):
    if i == 0:
        ans += B[0]
    elif i == N-1:
        ans += B[N-2]
    else:
        ans += min(B[i],B[i-1])

print(ans)

Submission status: Accepted

Solution code:
n = int(input())
b = list(map(int, input().split()))
a = [min(b[i],b[i+1]) for i in range(n-2)]
print(sum(a) + b[0] + b[-1])

Submission status: Accepted

Solution code:
N = int(input())
B = list(map(int, input().split()))

ans = B[0]
for i in range(N-2):
    ans += min(B[i], B[i+1])
print(ans+B[-1])

Submission status: Accepted

Solution code:
n=int(input())
l=list(map(int,input().split()))
l1=[0 for i in range(n)]
l1[0]=l[0]
l1[1]=l[0]
for i in range(0,n-2):
  if l[i]>l[i+1]:
    l1[i+1]=l[i+1]
  l1[i+2]=l[i+1]
sum=0
for i in l1:
  sum+=i
print(sum)

Submission status: Accepted

Solution code:
#!/usr/bin/python3
# -*- coding: utf-8 -*-


N = int(input())
Bn = list(map(int, input().split()))

An = [10**5 for _ in range(N)]
An[0] = Bn[0]
An[-1] = Bn[-1]
for i in range(1,N-1):
  An[i] = min(Bn[i],Bn[i-1])
print(sum(An))

Submission status: Accepted

Solution code:
n = int(input())
bb = list(map(int, input().split()))
bb = [bb[0]] + bb + [bb[-1]]
s = 0
for i in range(n):
    s += min([bb[i], bb[i+1]])
print(s)

Submission status: Accepted

Solution code:
import sys
sys.setrecursionlimit(10**7)
def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x) - 1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def II(): return int(sys.stdin.readline())
def SI(): return sys.stdin.readline().strip()
INF = 10 ** 18
MOD = 10 ** 9 + 7

debug = True
debug = False

def dprint(*objects):
    if debug == True:
        print(*objects)

def solve():
    N = II()
    b_list = LI()

    a_list = [0 for i in range(N)]
    for i in range(N):
        # i桁目はi-1とiのminで決めればいい
        if i == 0:
            a_list[i] = b_list[i]
        elif i == N-1:
            a_list[i] = b_list[i-1]
        else:
            a_list[i] = min(b_list[i], b_list[i-1])

    print(sum(a_list))

solve()

Submission status: Accepted

Solution code:
n = int(input())
b = list(map(int, input().split()))
a = b[0] + b[n - 2]

for i in range(n - 2):
    a = a + min(b[i], b[i + 1])

print(a)

Submission status: Accepted

Solution code:
def main():
    n = int(input())
    B = list(map(int, input().split()))
    ans = B[0]
    for b1, b2 in zip(B, B[1:]):
        ans += min(b1, b2)
    ans += B[-1]
    print(ans)


if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
#!/usr/bin/env python3
n = int(input())
b = list(map(int, input().split()))
ans = 0
for i in range(n - 2):
    ans += min(b[i], b[i + 1])
print(ans + b[0] + b[-1])

Submission status: Accepted

Solution code:
N = int(input())
B = list(map(int, input().split()))
ans = 0
ans+=B[0]
for i in range(1, N-1):
    ans+=min(B[i-1], B[i])
ans+=B[-1]
print(ans)

Submission status: Accepted

Solution code:
N = int(input())
B = list(map(int,input().split()))

ans = B[0] + B[-1]
for i in range(N-2):
    ans += min(B[i+1], B[i])

print(ans)

Submission status: Accepted

Solution code:
N,*B=map(int,open(0).read().split());print(B[0]+sum(min(i,j)for i,j in zip(B,B[1:]))+B[-1])

Submission status: Accepted

Solution code:
import sys

sys.setrecursionlimit(10**7)
INF = 10 ** 18
MOD = 10 ** 9 + 7
def LI(): return list(map(int, sys.stdin.readline().split()))
def II(): return int(sys.stdin.readline())
def LS(): return list(map(list, sys.stdin.readline().split()))
def S(): return list(sys.stdin.readline())[:-1]

def main():
    n = II()
    b_s = LI()
    a_s = [0 for i in range(n)]
    for i in range(n-1):
        if i == 0:
            a_s[i] = b_s[i]
            a_s[i+1] = b_s[i]
        else:
            if b_s[i] < b_s[i-1]:
                a_s[i] = b_s[i]
            a_s[i + 1] = b_s[i]
    print(int(sum(a_s)))

if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
N = int(input())
B = list(map(int, input().split()))

ans = 0
for i in range(N - 2):
    ans += min(B[i], B[i + 1])

print(ans + B[-1] + B[0])

Submission status: Accepted

Solution code:
N = int(input())
B = list(map(int, input().split()))

pre = 10 ** 6
res = 0
for b in B:
    if b < pre:
        pre = b
    res += pre
    pre = b

res += pre
print(res)

Submission status: Accepted

Solution code:
n = int(input())
bs = list(map(int, input().split()))
res = bs[0]
for b0, b1 in zip(bs, bs[1:]):
    res += min(b0, b1)
res += bs[-1]
print(res)

Submission status: Accepted

Solution code:
n=int(input())
hoge=list(map(int,input().split()))
ans=0
ans+=hoge[0]
ans+=hoge[-1]
for i in range(n-2):
  ans+=min(hoge[i],hoge[i+1])
  
print(ans)

Submission status: Accepted

Solution code:
n = int(input())
b= list(map(int, input().split()))

a = [0] * n
a[0] = b[0]
for i in range(1, n-1):
    a[i] = min(b[i], b[i-1])
a[n-1] = b[n-2]

print(sum(a))

Submission status: Accepted

Solution code:
def InputToInt():
    A = input().split()
    for i in range(len(A)):
        A[i] = int(A[i])
    return A
    
if __name__ == '__main__':
    N = int(input())
    A = InputToInt()
    c = A[0]+A[N-2]
    for i in range(N-2):
        c += min(A[i], A[i+1])
    print(c)

Submission status: Accepted

Solution code:
n = int(input())
b = list(map(int,input().split()))
ans = [0 for i in range(n)]

b.reverse()

ans[0] = b[0]
for i in range(n-2):
    ans[i+1] = min(b[i],b[i+1])

ans[-1] = b[-1]

# print(ans)
print(sum(ans))

Submission status: Accepted

Solution code:
n=int(input())
b=list(map(int,input().split()))
a=[100001]*n
for i in range(n-1):
  a[i]=min(a[i],b[i])
  a[i+1]=min(a[i+1],b[i])
print(sum(a))

Submission status: Accepted

Solution code:
N = int(input())
B = list(map(int,input().split(' ')))

ans = 0
for i in range(N-2):
	ans += min(B[i],B[i+1])

ans += B[0] + B[-1]
print(ans)

Submission status: Accepted

Solution code:
N=int(input())
B=list(map(int,input().split()))
A=[100000]*N
for i in range(N-1):
    A[i]=min(A[i],B[i])
    A[i+1]=min(A[i+1],B[i])
print(sum(A))

Submission status: Accepted

Solution code:
N = int(input())
B = list(map(int,input().split()))

A = [0] * N
A[0] = B[0]
A[N-1] = B[N-2]

for i in range(1,N-1):
  A[i] = min(B[i-1],B[i])

print(sum(A))

Submission status: Accepted

Solution code:
n=int(input())
a = [int(i) for i in input().split()]
s=0
b=[10**18]*(n)
for i in range(n-1):
  b[i]=min(a[i],b[i])
  b[i+1]=min(a[i],b[i+1])
print(sum(b))

Submission status: Accepted

Solution code:
n = int(input())
B = list(map(int, input().split()))

ans = 0
for i in range(n):
    if i == 0:
        a = B[0]
    elif i == n - 1:
        a = B[-1]
    else:
        a = min(B[i-1], B[i])
    ans += a
print(ans)

Submission status: Accepted

Solution code:
#!/usr/bin/env python
from __future__ import division, print_function

import os
import sys
from io import BytesIO, IOBase

if sys.version_info[0] < 3:
    from __builtin__ import xrange as range
    from future_builtins import ascii, filter, hex, map, oct, zip


def main():
    n = int(input())
    b = [int(i) for i in input().split()]

    s = b[0] + b[-1]

    p = b[0]
    for i in b[1:]:
        s += min(p, i)
        p = i

    print(s)


# region fastio

BUFSIZE = 8192


class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None

    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()

    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)


class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")


def print(*args, **kwargs):
    """Prints the values to a stream, or to sys.stdout by default."""
    sep, file = kwargs.pop("sep", " "), kwargs.pop("file", sys.stdout)
    at_start = True
    for x in args:
        if not at_start:
            file.write(sep)
        file.write(str(x))
        at_start = False
    file.write(kwargs.pop("end", "\n"))
    if kwargs.pop("flush", False):
        file.flush()


if sys.version_info[0] < 3:
    sys.stdin, sys.stdout = FastIO(sys.stdin), FastIO(sys.stdout)
else:
    sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)

input = lambda: sys.stdin.readline().rstrip("\r\n")

# endregion

if __name__ == "__main__":
    main()

Submission status: Accepted

Solution code:
n = int(input())
b = list(map(int, input().split()))

a = [0 for i in range(n)]

a[0] = b[0]

for ii in range(max(0,n-2)):
    i = ii+1
    a[i] = min(b[i-1],b[i])

a[n-1] = b[n-2]
print(sum(a))

Submission status: Accepted

Solution code:
inf = float('inf')

n = int(input())
b = tuple(map(int, input().split()))

a = [inf] * n
for i in range(n - 2, -1, -1):
    a[i + 1] = min(a[i + 1], b[i])
    a[i] = min(a[i], b[i])
print(sum(a))

Submission status: Accepted

Solution code:
def getlist():
    return list(map(int, input().split()))

N = int(input())
B = getlist()

ans = 0
ans += B[0]

for i in range(N - 2):
    ans += min(B[i], B[i + 1])

ans += B[-1]
print(ans)

Submission status: Accepted

Solution code:
n = int(input())
n -= 1
b = list(map(int, input().split()))
ans = b[-1]
for i in range(n-1)[::-1]:
    if  b[i] <= b[i+1]:
        ans += b[i]
    else:
        ans += b[i+1]
print(ans+b[0])

Submission status: Accepted

Solution code:
n=int(input())
b=list(map(int,input().split()))
b=[1<<32]+b+[1<<32]
res=[]
for i in range(1,n+1):
	res.append(min(b[i-1],b[i]))
print(sum(res))

Submission status: Accepted

Solution code:
n=int(input())
B=[int(i) for i in input().split()]

ans=0

for i in range(n-2):
    ans+=min(B[i],B[i+1])

ans+=B[0]
ans+=B[-1]

print(ans)

Submission status: Accepted

Solution code:
n = int(input())
bbb = list(map(int, input().split()))
ans = bbb[0]
ans += sum(map(min, zip(bbb, bbb[1:])))
ans += bbb[-1]
print(ans)

Submission status: Accepted

Solution code:
n=int(input())
blist = list(map(int, input().split()))

kazu=0

for i in range(n):
    if i==0:
        kazu+=blist[0]
    elif i==n-1:
        kazu+=blist[-1]
    else:
        kazu+=min(blist[i], blist[i-1])

print(kazu)

Submission status: Accepted

Solution code:
n=int(input())
l=list(map(int,input().split()))
ans=l[0]+l[-1]
for i in range(n-2):
    ans+=min(l[i],l[i+1])
print(ans)

Submission status: Accepted

Solution code:
N = int(input())
Bs = list(map(int, input().split())) + [float('inf')]
ans = Bs[0]
for i in range(1, N):
  a, b = Bs[i-1], Bs[i]
  ans += a if a <= b else b
print(ans)

Submission status: Accepted

Solution code:
n = int(input())
b = list(map(int, input().split()))
ans = 0
for i in range(n-2):
    ans += min(b[i], b[i+1])
ans += b[0] + b[-1]
print(ans)

Submission status: Accepted

Solution code:
n=int(input())
B=list(map(int,input().split()))
ans=B[0]+B[n-2]
for i in range(n-2):
    ans+=min(B[i],B[i+1])
print(ans)

Submission status: Accepted

Solution code:
#!/usr/bin/env python3
import sys
INF = float("inf")


def solve(N: int, B: "List[int]"):
    ans = B[-1]
    pre = 0
    for i in range(N-2, 0, -1):
        ans += min(B[i], B[i-1])
    ans += B[0]
    print(ans)
    return


def main():

    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    B = [int(next(tokens)) for _ in range(N - 1)]  # type: "List[int]"
    solve(N, B)


if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
N = int(input())
A = [0] * N
B = [int(x) for x in input().split()]
A[0] = B[0]
A[-1] = B[-1]
for i in range(N - 2):
  A[i + 1] = min(B[i], B[i + 1])
print(sum(A))

Submission status: Accepted

Solution code:
n = int(input())
b = list(map(int, input().split()))
ans = b[0] + b[n - 2]
for i in range(1, n - 1):
	ans += min(b[i], b[i - 1])
print(ans)

Submission status: Accepted

Solution code:
INF = 10**6

N = int(input())
Bs = [INF] + list(map(int, input().split())) + [INF]

ans = 0
for i in range(N):
    ans += min(Bs[i], Bs[i+1])

print(ans)

Submission status: Accepted

Solution code:
N=int(input())
B=list(map(int,input().split()))
ans=0
ans+=B[0]
ans+=B[-1]

for i in range(N-2):
	ans+=min(B[i],B[i+1])

print(ans)

Submission status: Accepted

Solution code:
N = int(input())
inf = 10 ** 6
B = [inf] + list(map(int, input().split())) + [inf]
A = []
for i in range(N):
  A.append(min(B[i], B[i + 1]))
print(sum(A))