Problem:


Score : 500 points

Problem Statement

There are N towns numbered 1 to N and M roads. The i-th road connects Town A_i and Town B_i bidirectionally and has a length of C_i.

Takahashi will travel between these towns by car, passing through these roads. The fuel tank of his car can contain at most L liters of fuel, and one liter of fuel is consumed for each unit distance traveled. When visiting a town while traveling, he can full the tank (or choose not to do so). Travel that results in the tank becoming empty halfway on the road cannot be done.

Process the following Q queries:

The tank is now full. Find the minimum number of times he needs to full his tank while traveling from Town s_i to Town t_i. If Town t_i is unreachable, print -1.

Constraints

All values in input are integers.

2 \leq N \leq 300

0 \leq M \leq \frac{N(N-1)}{2}

1 \leq L \leq 10^9

1 \leq A_i, B_i \leq N

A_i \neq B_i

\left(A_i, B_i\right) \neq \left(A_j, B_j\right) (if i \neq j)

\left(A_i, B_i\right) \neq \left(B_j, A_j\right) (if i \neq j)

1 \leq C_i \leq 10^9

1 \leq Q \leq N\left(N-1\right)

1 \leq s_i, t_i \leq N

s_i \neq t_i

\left(s_i, t_i\right) \neq \left(s_j, t_j\right) (if i \neq j)

Input

Input is given from Standard Input in the following format:

N M L
A_1 B_1 C_1
:
A_M B_M C_M
Q
s_1 t_1
:
s_Q t_Q

Output

Print Q lines.

The i-th line should contain the minimum number of times the tank needs to be fulled while traveling from Town s_i to Town t_i. If Town t_i is unreachable, the line should contain -1 instead.

Sample Input 1

3 2 5
1 2 3
2 3 3
2
3 2
1 3

Sample Output 1

0
1

To travel from Town 3 to Town 2, we can use the second road to reach Town 2 without fueling the tank on the way.

To travel from Town 1 to Town 3, we can first use the first road to get to Town 2, full the tank, and use the second road to reach Town 3.

Sample Input 2

4 0 1
1
2 1

Sample Output 2

-1

There may be no road at all.

Sample Input 3

5 4 4
1 2 2
2 3 2
3 4 3
4 5 2
20
2 1
3 1
4 1
5 1
1 2
3 2
4 2
5 2
1 3
2 3
4 3
5 3
1 4
2 4
3 4
5 4
1 5
2 5
3 5
4 5

Sample Output 3

0
0
1
2
0
0
1
2
0
0
0
1
1
1
0
0
2
2
1
0



Sample input:
3 2 5
1 2 3
2 3 3
2
3 2
1 3


Sample output:
0
1

Submission status: Accepted

Solution code:
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

from scipy.sparse.csgraph import floyd_warshall
from scipy.sparse import csr_matrix

import numpy as np

N,M,L = map(int,readline().split())
ABCPST = np.array(read().split(),np.int64)
ABC = ABCPST[:M+M+M]
A = ABC[::3]; B = ABC[1::3]; C = ABC[2::3]
ST = ABCPST[M+M+M+1:]
S = ST[::2]; T = ST[1::2]

# とりあえず、補給抜きにして最短距離を求める
graph = csr_matrix((C,(A,B)),(N+1,N+1))
dist_mat = floyd_warshall(graph,directed=False)

# 補給なしに行ける移動を1手とする

graph2 = np.full((N+1,N+1),np.inf)
np.fill_diagonal(graph2,0)
graph2[dist_mat<=L] = 1

dist_mat2 = floyd_warshall(graph2,directed=False)

dist_mat2[dist_mat2 == np.inf] = 0
dist_mat2 = (dist_mat2).astype(int)

x = dist_mat2[S,T] - 1

print('\n'.join(x.astype(str)))

Submission status: Accepted

Solution code:
n,m,L=map(int,input().split())
l=[list(map(int,input().split())) for i in range(m)]
q=int(input())
ql=[list(map(int,input().split())) for i in range(q)]
distance=[[10**18]*n for i in range(n)]
for i in range(m):
  if l[i][2]<=L:
    distance[l[i][0]-1][l[i][1]-1]=l[i][2]
    distance[l[i][1]-1][l[i][0]-1]=l[i][2]
for i in range(n):
  for j in range(n):
    for k in range(n):
      distance[j][k]=min(distance[j][k],distance[j][i]+distance[i][k])
 
distance2=[[10**18]*n for i in range(n)]
for i in range(n):
  for j in range(n):
    if distance[i][j]<=L:
      distance2[i][j]=1
      distance2[j][i]=1
for i in range(n):
  for j in range(n):
    for k in range(n):
      distance2[j][k]=min(distance2[j][k],distance2[j][i]+distance2[i][k])
 
for i in range(q):
  if distance2[ql[i][0]-1][ql[i][1]-1]>=10**18:
    print(-1)
  else:
    print(distance2[ql[i][0]-1][ql[i][1]-1]-1)

Submission status: Accepted

Solution code:
import sys
sys.setrecursionlimit(2147483647)
INF=float("inf")
MOD=10**9+7
input=lambda :sys.stdin.readline().rstrip()
def resolve():
    n,m,L=map(int,input().split())
    A=[[INF]*n for _ in range(n)]
    for _ in range(m):
        a,b,c=map(int,input().split())
        a-=1; b-=1
        A[a][b]=A[b][a]=c
    from itertools import product
    for k,i,j in product(range(n),repeat=3):
        A[i][j]=min(A[i][j],A[i][k]+A[k][j])
    B=[[INF]*n for _ in range(n)]
    for i,j in product(range(n),repeat=2):
        if(A[i][j]<=L): B[i][j]=1
    for k,i,j in product(range(n),repeat=3):
        B[i][j]=min(B[i][j],B[i][k]+B[k][j])
    Q=int(input())
    for _ in range(Q):
        s,t=map(int,input().split())
        s-=1; t-=1
        print(B[s][t]-1 if(B[s][t]!=INF) else -1)
resolve()

Submission status: Accepted

Solution code:
import sys

def input():
    return sys.stdin.readline()[:-1]

N,M,L = list(map(int,input().split()))

e_list = [[] for i in range(N)]

def warshall_floyd(d):
    #d[i][j]: iからjへの最短距離
    for k in range(N):
        for i in range(N):
            for j in range(N):
                d[i][j] = min(d[i][j],d[i][k] + d[k][j])
    return d

d = [[float("inf") for i in range(N)] for i in range(N)] 
#d[u][v] : 辺uvのコスト(存在しないときはinf)
for i in range(M):
    x,y,z = list(map(int,input().split()))
    if z<=L:
        d[x-1][y-1] = z
        d[y-1][x-1] = z

for i in range(N):
    d[i][i] = 0 #自身のところに行くコストは０

d = warshall_floyd(d)

e_list = [[] for i in range(N)]

d2 = [[float("inf") for i in range(N)] for i in range(N)]

for i in range(N):
    for j in range(i+1,N):
        if d[i][j] <= L:
            d2[i][j] = 1
            d2[j][i] = 1

d2 = warshall_floyd(d2)

Q = int(input())
for i in range(Q):
    s,t = list(map(int,input().split()))
    s,t = s-1,t-1
    if d2[s][t]>10**9:
        print(-1)
    else:
        print(d2[s][t]-1)

Submission status: Accepted

Solution code:
# ABC143E - Travel by Car
# https://atcoder.jp/contests/abc143/submissions/8051337
import sys
import numpy as np

from scipy.sparse import csr_matrix
from scipy.sparse.csgraph import floyd_warshall


def main():
    # FW -> once more FW to edges <= L
    read = sys.stdin.buffer.read
    N, M, L, *X = map(int, read().split())
    ABC, ST = X[: 3 * M], X[3 * M + 1 :]
    A, B, C, S, T = ABC[::3], ABC[1::3], ABC[2::3], ST[::2], ST[1::2]

    G = csr_matrix((C, (A, B)), (N + 1, N + 1))
    dist = floyd_warshall(G, directed=0)  # naive distance

    # assume distance within L as 1 and compute the number of fueling
    modified_G = np.full((N + 1, N + 1), np.inf)
    np.fill_diagonal(modified_G, 0)
    modified_G[dist <= L] = 1
    modified_dist = floyd_warshall(modified_G, directed=0)
    modified_dist[modified_dist == np.inf] = 0
    modified_dist = (modified_dist).astype(int)

    ans = modified_dist[S, T] - 1
    print("\n".join(ans.astype(str)))


if __name__ == "__main__":
    main()

Submission status: Accepted

Solution code:
# ABC143E - Travel by Car
import numpy as np

from scipy.sparse import csr_matrix
from scipy.sparse.csgraph import floyd_warshall


def main():
    # FW -> once more FW to edges <= L
    global L, G, dist, ancestors
    N, M, L, *X = map(int, open(0).read().split())
    ABC, ST = X[: 3 * M], X[3 * M + 1 :]
    A, B, C, S, T = ABC[::3], ABC[1::3], ABC[2::3], ST[::2], ST[1::2]

    G = csr_matrix((C, (A, B)), (N + 1, N + 1))
    dist = floyd_warshall(G, directed=0)

    modified_G = np.full((N + 1, N + 1), np.inf)
    np.fill_diagonal(modified_G, 0)
    modified_G[dist <= L] = 1
    modified_dist = floyd_warshall(modified_G, directed=0)
    modified_dist[modified_dist == np.inf] = 0
    modified_dist = (modified_dist).astype(int)
    
    ans = modified_dist[S, T] - 1
    print("\n".join(ans.astype(str)))


if __name__ == "__main__":
    main()

Submission status: Accepted

Solution code:
import sys
input = sys.stdin.readline


n, m, l = map(int, input().split())
info = [list(map(int, input().split())) for i in range(m)]
graph = [[] for i in range(n)]
for i in range(m):
    a, b, cost = info[i]
    if cost > l:
        continue
    a -= 1
    b -= 1
    graph[a].append((b, cost))
    graph[b].append((a, cost))


def warshall_floid(graph):
    """warshall-floid法: 各頂点から各頂点への最短距離を求める
    重み付きグラフgraphは隣接リストで与えられる
    計算量: O(|N|^3)
    """
    n = len(graph)
    INF = 10**18
    dp = [[INF]*n for i in range(n)]
    for i in range(n):
        dp[i][i] = 0

    for i in range(n):
        for j, cost in graph[i]:
            dp[i][j] = cost
            dp[j][i] = cost

    for k in range(n):
        for i in range(n):
            for j in range(n):
                dp[i][j] = min(dp[i][j], dp[i][k] + dp[k][j])

    return dp

def warshall_floid_matrix(matrix):
    """warshall-floid法: 各頂点から各頂点への最短距離を求める
    matrix[i][j] := 頂点iから頂点jへの距離（頂点iから頂点jへ到達できないときはINFを代入しておく）
    計算量: O(|N|^3)
    """
    n = len(matrix)
    dp = matrix
    for k in range(n):
        for i in range(n):
            for j in range(n):
                dp[i][j] = min(dp[i][j], dp[i][k] + dp[k][j])
    return dp

dp1 = warshall_floid(graph)
INF = 10**18
dp2 = [[INF]*n for i in range(n)]
for i in range(n):
    for j in range(n):
        if dp1[i][j] <= l:
            dp2[i][j] = 1
ans = warshall_floid_matrix(dp2)         

q = int(input())
query = [list(map(int, input().split())) for i in range(q)]
for i in range(q):
    a, b = query[i]
    a -= 1
    b -= 1
    if ans[a][b] == 10**18:
        print(-1)
    else:
        print(ans[a][b] - 1)

Submission status: Accepted

Solution code:
import sys
input = sys.stdin.buffer.readline
sys.setrecursionlimit(10**7)
INF = 10**12
 
n, m, l = [int(item) for item in input().split()]
dist = [[INF] * n for _ in range(n)]
for i in range(m):
    a, b, c = [int(item) for item in input().split()]
    a -= 1; b -= 1
    dist[a][b] = c
    dist[b][a] = c
 
for i in range(n):
    dist[i][i] = 0
 
for k in range(n):
    for i in range(n):
        for j in range(n):
            dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j])
 
for i in range(n):
    for j in range(n):
        if i == j:
            dist[i][j] = 0
        elif dist[i][j] <= l:
            dist[i][j] = 1
        else:
            dist[i][j] = INF
 
for k in range(n):
    for i in range(n):
        for j in range(n):
            dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j])
 
q = int(input())
for i in range(q):
    s, t = [int(item) - 1 for item in input().split()]
    if dist[s][t] == INF:
        print(-1)
    else:
        print(dist[s][t] - 1)

Submission status: Accepted

Solution code:
from scipy.sparse import*
f=csgraph.floyd_warshall
I=9e9
n,m,l,*t=map(int,open(0).read().split())
d=eval('[I]*-~n,'*-~n)
for a,b,c in zip(*[iter(t[:m*3])]*3):d[a][b]=d[b][a]=c
d=f(d)
d[d>l]=I
d[d<I]=1
d=f(d)
for i in zip(*[iter(t[m*3+1:])]*2):print((I>d[i])*int(d[i])-1)

Submission status: Accepted

Solution code:

N , M , L = map(int,input().split())

lis = [ [float("inf")] * N for i in range(N) ]


for i in range(M):

    A,B,C = map(int,input().split())
    A -= 1
    B -= 1

    lis[A][B] = C
    lis[B][A] = C
    
for k in range(N):

    for i in range(N):

        for j in range(i):    

            if lis[i][j] > lis[i][k] + lis[k][j]:

                lis[i][j] = lis[i][k] + lis[k][j]
                lis[j][i] = lis[i][k] + lis[k][j]

lis2 = [ [float("inf")] * N for i in range(N) ]


for i in range(N):

    for j in range(i):

        if lis[i][j] <= L:
            lis2[i][j] = 1
            lis2[j][i] = 1

for k in range(N):

    for i in range(N):

        for j in range(i):

            if lis2[i][j] > lis2[i][k] + lis2[k][j]:

                lis2[i][j] = lis2[i][k] + lis2[k][j]
                lis2[j][i] = lis2[i][k] + lis2[k][j]

Q = int(input())

for i in range(Q):

    s,t = map(int,input().split())
    s -= 1
    t -= 1

    if lis2[s][t] == float("inf"):
        print (-1)
    else:
        print (lis2[s][t]-1)

Submission status: Accepted

Solution code:

N , M , L = map(int,input().split())

lis = [ [float("inf")] * N for i in range(N) ]

for i in range(N):

    lis[i][i] = 0

for i in range(M):

    A,B,C = map(int,input().split())
    A -= 1
    B -= 1

    lis[A][B] = C
    lis[B][A] = C
    
for k in range(N):

    for i in range(N):

        for j in range(i):    

            if lis[i][j] > lis[i][k] + lis[k][j]:

                lis[i][j] = lis[i][k] + lis[k][j]
                lis[j][i] = lis[i][k] + lis[k][j]

lis2 = [ [float("inf")] * N for i in range(N) ]

for i in range(N):

    lis2[i][i] = 0

for i in range(N):

    for j in range(i):

        if lis[i][j] <= L:
            lis2[i][j] = 1
            lis2[j][i] = 1

for k in range(N):

    for i in range(N):

        for j in range(i):

            if lis2[i][j] > lis2[i][k] + lis2[k][j]:

                lis2[i][j] = lis2[i][k] + lis2[k][j]
                lis2[j][i] = lis2[i][k] + lis2[k][j]

Q = int(input())

for i in range(Q):

    s,t = map(int,input().split())
    s -= 1
    t -= 1

    if lis2[s][t] == float("inf"):
        print (-1)
    else:
        print (lis2[s][t]-1)

Submission status: Accepted

Solution code:
from scipy.sparse import*
f=csgraph.floyd_warshall
I=9e9
n,m,l,*t=map(int,open(0).read().split())
d=eval('[I]*-~n,'*-~n)
for a,b,c in zip(*[iter(t[:m*3])]*3):d[a][b]=c
d=f(d,0)
d[d>l]=I
d[d<I]=1
d=f(d)
for i in zip(*[iter(t[m*3+1:])]*2):
	print((I>d[i])*int(d[i])-1)

Submission status: Accepted

Solution code:
import numpy as np
from scipy.sparse.csgraph import dijkstra

N, M, L = map(int, input().split())
abc = []
for _ in range(M):
    abc.append(list(map(int, input().split())))
abc = abc

Q = int(input())
query = []
for _ in range(Q):
    query.append(tuple(map(int, input().split())))
distance = np.zeros((N, N))
for (a, b, c) in abc:
    distance[a - 1, b - 1] = c
    distance[b - 1, a - 1] = c

x = np.where(dijkstra(distance) <= L, 1, 0)
x -= np.eye(N).astype(np.int64)
x = dijkstra(x)
for s, t in query:
    ans = x[s - 1, t - 1]
    if np.isinf(ans):
        print(-1)
    else:
        print(int(ans) - 1)

Submission status: Accepted

Solution code:
# -*- coding: utf-8 -*-
import random
import sys

sys.setrecursionlimit(100000)
input = sys.stdin.readline

INF = 2**62-1

def read_int():
    return int(input())


def read_int_n():
    return list(map(int, input().split()))


def warshall_floyd(g):
    N = len(g)
    for k in range(N):
        for i in range(N):
            for j in range(N):
                g[i][j] = min(g[i][j], g[i][k] + g[k][j])
    return g


def slv(N, M, L, ABC, Q, ST):
    g = [[INF]*(N) for _ in range(N)]

    for a, b, c in ABC:
        if c > L:
            continue
        g[a-1][b-1] = c
        g[b-1][a-1] = c

    d = warshall_floyd(g)

    gg = [[INF]*(N) for _ in range(N)]
    for u in range(N):
        for v in range(N):
            if d[u][v] <= L:
                gg[u][v] = 1

    d = warshall_floyd(gg)

    for s, t in ST:
        c = d[s-1][t-1]
        if c != INF:
            print(c-1)
        else:
            print(-1)


def main():
    N, M, L = read_int_n()
    ABC = [read_int_n() for _ in range(M)]
    Q = read_int()
    ST = [read_int_n() for _ in range(Q)]

    (slv(N, M, L, ABC, Q, ST))


if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
# -*- coding: utf-8 -*-
import random
import sys

sys.setrecursionlimit(100000)
input = sys.stdin.readline

INF = 10**11

def read_int():
    return int(input())


def read_int_n():
    return list(map(int, input().split()))


def warshall_floyd(g):
    N = len(g)
    for k in range(N):
        for i in range(N):
            for j in range(N):
                g[i][j] = min(g[i][j], g[i][k] + g[k][j])
    return g


def slv(N, M, L, ABC, Q, ST):
    g = [[INF]*(N) for _ in range(N)]

    for a, b, c in ABC:
        if c > L:
            continue
        g[a-1][b-1] = c
        g[b-1][a-1] = c

    d = warshall_floyd(g)

    gg = [[INF]*(N) for _ in range(N)]
    for u in range(N):
        for v in range(N):
            if d[u][v] <= L:
                gg[u][v] = 1

    d = warshall_floyd(gg)

    for s, t in ST:
        c = d[s-1][t-1]
        if c != INF:
            print(c-1)
        else:
            print(-1)


def main():
    N, M, L = read_int_n()
    ABC = [read_int_n() for _ in range(M)]
    Q = read_int()
    ST = [read_int_n() for _ in range(Q)]

    (slv(N, M, L, ABC, Q, ST))


if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
# -*- coding: utf-8 -*-
import random
import sys

sys.setrecursionlimit(100000)
input = sys.stdin.readline

INF = 10**11

def read_int():
    return int(input())


def read_int_n():
    return list(map(int, input().split()))


def warshall_floyd(g):
    d = g
    N = len(g)
    for k in range(N):
        for i in range(N):
            for j in range(N):
                d[i][j] = min(d[i][j], d[i][k] + d[k][j])
    return d


def slv(N, M, L, ABC, Q, ST):
    g = [[INF]*(N) for _ in range(N)]

    for a, b, c in ABC:
        if c > L:
            continue
        g[a-1][b-1] = c
        g[b-1][a-1] = c

    d = warshall_floyd(g)

    gg = [[INF]*(N) for _ in range(N)]
    for u in range(N):
        for v in range(N):
            if d[u][v] <= L:
                gg[u][v] = 1

    d = warshall_floyd(gg)

    for s, t in ST:
        c = d[s-1][t-1]
        if c != INF:
            print(c-1)
        else:
            print(-1)


def main():
    N, M, L = read_int_n()
    ABC = [read_int_n() for _ in range(M)]
    Q = read_int()
    ST = [read_int_n() for _ in range(Q)]

    (slv(N, M, L, ABC, Q, ST))


if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
# -*- coding: utf-8 -*-
import random
import sys

sys.setrecursionlimit(100000)
input = sys.stdin.readline

INF = 10**11

def read_int():
    return int(input())


def read_int_n():
    return list(map(int, input().split()))


def warshall_floyd(g):
    d = g
    N = len(g)
    for k in range(N):
        for i in range(N):
            for j in range(N):
                d[i][j] = min(d[i][j], d[i][k] + d[k][j])
    return d


def slv(N, M, L, ABC, Q, ST):
    g = [[INF]*(N) for _ in range(N)]
    for i in range(N):
        g[i][i] = 0
    for a, b, c in ABC:
        if c > L:
            continue
        g[a-1][b-1] = c
        g[b-1][a-1] = c

    d = g
    for k in range(N):
        for i in range(N):
            for j in range(N):
                d[i][j] = min(d[i][j], d[i][k] + d[k][j])
    gg = [[INF]*(N) for _ in range(N)]
    for u in range(N):
        for v in range(N):
            if d[u][v] <= L:
                gg[u][v] = 1

    d = gg
    for k in range(N):
        for i in range(N):
            for j in range(N):
                d[i][j] = min(d[i][j], d[i][k] + d[k][j])

    for s, t in ST:
        c = d[s-1][t-1]
        if c != INF:
            print(c-1)
        else:
            print(-1)


def main():
    N, M, L = read_int_n()
    ABC = [read_int_n() for _ in range(M)]
    Q = read_int()
    ST = [read_int_n() for _ in range(Q)]

    (slv(N, M, L, ABC, Q, ST))


if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
def slv():
    import sys
    input = sys.stdin.readline
    N, M, L = list(map(int, input().rstrip('\n').split()))
    INF = 10**11
    g = [[INF]*(N) for _ in range(N)]
    gg = [[INF]*(N) for _ in range(N)]

    for i in range(N):
        g[i][i] = 0
    for _ in range(M):
        a, b, c = list(map(int, input().rstrip('\n').split()))
        if c <= L:
            g[a-1][b-1] = c
            g[b-1][a-1] = c
    
    for k in range(N):
        for i in range(N):
            for j in range(N):
                g[i][j] = min(g[i][j], g[i][k] + g[k][j])
    
    for u in range(N):
        for v in range(N):
            if g[u][v] <= L:
                gg[u][v] = 1
    
    for k in range(N):
        for i in range(N):
            for j in range(N):
                gg[i][j] = min(gg[i][j], gg[i][k] + gg[k][j])

    Q = int(input())
    for _ in range(Q):
        s, t = list(map(int, input().rstrip('\n').split()))
        c = gg[s-1][t-1]
        if c != INF:
            print(c-1)
        else:
            print(-1)



def main():
    slv()

if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
from scipy.sparse.csgraph import floyd_warshall
N,M,L=map(int,input().split())
inf=10**9+1

distance=[[inf for n in range(N)] for n in range(N)]
for n in range(N):
    distance[n][n]=0
for m in range(M):
    a,b,c=map(int,input().split())
    distance[a-1][b-1]=c
    distance[b-1][a-1]=c
distance=floyd_warshall(distance)

distance2=[[inf for n in range(N)] for n in range(N)]
for i in range(N):
    for j in range(N):
        if distance[i][j]<=L:
            distance2[i][j]=1
for n in range(N):
    distance2[n][n]=0
distance2=floyd_warshall(distance2)

Q=int(input())
for q in range(Q):
    s,t=map(int,input().split())
    if distance2[s-1][t-1]==inf:
        print(-1)
    else:
        print(int(distance2[s-1][t-1]-1))

Submission status: Accepted

Solution code:
import sys


def main():
	input = sys.stdin.readline
	N, M, L = list(map(int,input().split()))
	P = [list(map(int,input().split())) for i in range(M)]
	Q = int(input())
	st = [list(map(int,input().split())) for i in range(Q)]

	neighbor = [[] for i in range(N)]
	for s,e,d in P:
		if d<=L:
			neighbor[s-1].append((e-1,d))
			neighbor[e-1].append((s-1,d))
		# if d<=L:
		# 	neighbor[s-1][e-1] = neighbor[e-1][s-1] = d

	# print(neighbor)
	# start, end = 2,1

	fuellist = [0]*N
	def bfs(start, end):
		# fuel = [[10000000,L+1] for i in range(N)]
		fuelc, fuelm = [10000000]*N, [L+1]*N
		# fuel[start][0] = 0
		# fuel[start][1] = L
		fuelc[start], fuelm[start] = 0, L
		queue = [start]
		while len(queue)>0:
			nq = []						# next target node
			nq_append = nq.append
			for i in queue:				# target node
				oc, om = fuelc[i], fuelm[i]
				for j, d in neighbor[i]:
				# for j, d in enumerate(neighbor[i]):	# next node
					# if d==10**10: continue
					if om<d:
						nc = oc+1
						nm = L-d
					else:
						nc = oc
						nm = om-d

					# print(i,j,nc,nm)

					if nc<fuelc[j]:
						fuelc[j], fuelm[j] = nc, nm
						nq_append(j)
					elif nc==fuelc[j] and nm>fuelm[j]:
						fuelm[j] = nm
						nq_append(j)

			queue = nq					# update target node

		# ans = fuel[end][0]
		ans = fuelc[end]
		if ans==10000000: ans = -1

		fuellist[start] = fuelc

		print(ans)

	for s, t in st:
		start, end = s-1, t-1

		if fuellist[start]!=0:
			ans = fuellist[start][end]
			if ans==10000000: ans = -1
			print(ans)
		elif fuellist[end]!=0:
			ans = fuellist[end][start]
			if ans==10000000: ans = -1
			print(ans)
		else:
			bfs(start,end)


if __name__ == '__main__':
	main()

Submission status: Accepted

Solution code:
def warshall_floyd(G):
    '''
    G: N * N Array (Adjacency matrix)
    ret: N * N Array (Minimum path)
    '''
    import copy
    ret = copy.deepcopy(G)
    for k in range(N):
        for i in range(N):
            for j in range(N):
                ret[i][j] = min(ret[i][j], ret[i][k] + ret[k][j])
    return ret


INF = 10 ** 10
N, M, L = map(int, input().split())

G = [[INF] * N for _ in range(N)]
for i in range(M):
    A, B, C = map(int, input().split())
    G[A - 1][B - 1], G[B - 1][A - 1] = C, C

MinG = warshall_floyd(G)
GL = [[1 if MinG[i][j] <= L else INF for j in range(N)] for i in range(N)]
MinGL = warshall_floyd(GL)

Q = int(input())
for _ in range(Q):
    s, t = map(int, input().split())
    print(-1 if MinGL[s - 1][t - 1] == INF else MinGL[s - 1][t - 1] - 1)

Submission status: Accepted

Solution code:
def e_travel_by_car(INF=float('inf')):
    from copy import deepcopy
    from scipy.sparse.csgraph import floyd_warshall
    N, M, L = [int(i) for i in input().split()]
    Roads = [[int(i) for i in input().split()] for j in range(M)]
    Q = int(input())
    Queries = [[int(i) for i in input().split()] for j in range(Q)]

    graph = [[INF] * N for _ in range(N)]
    for k in range(N):
        graph[k][k] = 0
    fuel = deepcopy(graph)

    for a, b, c in Roads:
        graph[a - 1][b - 1] = graph[b - 1][a - 1] = c
    dist = floyd_warshall(graph)

    for i in range(N):
        for j in range(i):
            fuel[i][j] = fuel[j][i] = int(dist[i][j] <= L)
    fuel = floyd_warshall(fuel)

    ans = [-1 if fuel[s - 1][t - 1] == INF else int(fuel[s - 1][t - 1]) - 1 for s, t in Queries]
    return '\n'.join(map(str, ans))

print(e_travel_by_car())

Submission status: Accepted

Solution code:
def e_travel_by_car(INF=float('inf')):
    from copy import deepcopy
    from scipy.sparse.csgraph import floyd_warshall
    N, M, L = [int(i) for i in input().split()]
    Roads = [[int(i) for i in input().split()] for j in range(M)]
    Q = int(input())
    Queries = [[int(i) for i in input().split()] for j in range(Q)]

    graph = [[INF] * N for _ in range(N)]
    for k in range(N):
        graph[k][k] = 0
    fuel = deepcopy(graph)

    for a, b, c in Roads:
        graph[a - 1][b - 1] = graph[b - 1][a - 1] = c
    dist = floyd_warshall(graph)

    for i in range(N):
        for j in range(N):
            fuel[i][j] = int(dist[i][j] <= L)
    fuel = floyd_warshall(fuel)

    ans = [-1 if fuel[s - 1][t - 1] == INF else int(fuel[s - 1][t - 1]) - 1 for s, t in Queries]
    return '\n'.join(map(str, ans))

print(e_travel_by_car())

Submission status: Accepted

Solution code:
N, M, L = map(int,input().split(' '))
Ms=[]
inf = 10**11
for i in range(N+1):
    #for j in range(N):
    Ms.append([inf]*(N+1) )
#print(d)
#print(d[1][1])
for i in range(M):
    a,b,c = map(int,input().split(' '))
    #print(a,b,c)
    Ms[a][b] = c
    Ms[b][a] = c
    #print(Ms)
Q = int(input())

def warshall_floyd(Ms):
    for k in range(1,len(Ms)):
        for i in range(1,len(Ms)):
            for j in range(1,len(Ms)):
                Ms[i][j]=min(Ms[i][j],Ms[i][k]+Ms[k][j])
    return Ms

Ms = warshall_floyd(Ms)
#print(Ms)
#print("Ms",Ms[3][2],Ms[2][3])
#Ls = Ms.copy()
Ls = Ms
for i in range(N+1):
    for j in range(N+1):
        if Ls[i][j] <= L:
            Ls[i][j] = 1
        else:
            Ls[i][j]=inf
#print("Ls",Ls[3][2])
Ls = warshall_floyd(Ls)
#print(Ls)
for i in range(Q):
    s,t = map(int,input().split(' '))
    if Ls[s][t] == inf:
        print(-1)
    else:
        print(Ls[s][t]-1)

Submission status: Accepted

Solution code:
from scipy.sparse import*
f=csgraph.floyd_warshall
I=9e9
n,m,l,*t=map(int,open(0).read().split())
d=eval('[I]*-~n,'*-~n)
for a,b,c in zip(*[iter(t[:m*3])]*3):d[a][b]=d[b][a]=c
d=f(d)
d[d>l]=I
d[d<I]=1
d=f(d)
d[d>I]=I
for i in zip(*[iter(t[m*3+1:])]*2):print(int(d[i]%I-1))

Submission status: Accepted

Solution code:
from scipy.sparse.csgraph import floyd_warshall

N, M, L, *I = map(int, open(0).read().split())
ABC, ST = I[:3 * M], I[3 * M + 1:]

E = [[0] * N for _ in range(N)]
for a, b, c in zip(*[iter(ABC)] * 3):
    E[a - 1][b - 1] = E[b - 1][a - 1] = c

E = floyd_warshall(E)
E = [[(eij <= L) for j, eij in enumerate(ei)] for i, ei in enumerate(E)]
E = floyd_warshall(E)

INF = float("inf")

print("\n".join("-1" if E[s - 1][t - 1] == INF else str(int(E[s - 1][t - 1] - 1)) for s, t in zip(*[iter(ST)] * 2)))

Submission status: Accepted

Solution code:
from scipy.sparse.csgraph import floyd_warshall

N, M, L, *I = map(int, open(0).read().split())
ABC, ST = I[:3 * M], I[3 * M + 1:]

E = [[0] * N for _ in range(N)]
for a, b, c in zip(*[iter(ABC)] * 3):
    E[a - 1][b - 1] = E[b - 1][a - 1] = c

E = floyd_warshall(E)

for i, ei in enumerate(E):
    for j, eij in enumerate(ei):
        E[i][j] = (eij <= L)

E = floyd_warshall(E)

INF = float("inf")

A = []
for s, t in zip(*[iter(ST)] * 2):
    a = E[s - 1][t - 1] - 1
    A.append("-1" if a == INF else str(int(a)))

print("\n".join(A))

Submission status: Accepted

Solution code:
from scipy.sparse.csgraph import floyd_warshall

N, M, L, *I = map(int, open(0).read().split())
ABC, ST = I[:3 * M], I[3 * M + 1:]

E = [[0] * N for _ in range(N)]
for a, b, c in zip(*[iter(ABC)] * 3):
    E[a - 1][b - 1] = E[b - 1][a - 1] = c

E = floyd_warshall(E)

for i in range(N):
    for j in range(N):
        E[i][j] = (E[i][j] <= L)

E = floyd_warshall(E)

INF = float("inf")

A = []
for s, t in zip(*[iter(ST)] * 2):
    a = E[s - 1][t - 1] - 1
    A.append("-1" if a == INF else str(int(a)))

print("\n".join(A))

Submission status: Accepted

Solution code:
from subprocess import*
call(('python3','-c',"""
from scipy.sparse import*
s=csgraph.floyd_warshall
n,m,l,*t=map(int,open(0).read().split())
d=eval('[9e9]*-~n,'*-~n)
for a,b,c in zip(*[iter(t[:m*3])]*3):d[a][b]=d[b][a]=c
d=s(d)
d[d>l]=9e9
d[d<=l]=1
d=s(d)
d[d>9e9]=9e9
for s,t in zip(*[iter(t[m*3+1:])]*2):print(int(d[s,t]%9e9-1))
"""))

Submission status: Accepted

Solution code:
from scipy.sparse import*
s=csgraph.floyd_warshall
n,m,l,*t=map(int,open(0).read().split())
d=eval('[9e9]*-~n,'*-~n)
for a,b,c in zip(*[iter(t[:m*3])]*3):d[a][b]=d[b][a]=c
d=s(d)
d[d>l]=9e9
d[d<=l]=1
d=s(d)
d[d>9e9]=9e9
for s,t in zip(*[iter(t[m*3+1:])]*2):print(int(d[s,t]%9e9-1))

Submission status: Accepted

Solution code:
from scipy.sparse.csgraph import floyd_warshall

N, M, L, *I = map(int, open(0).read().split())
ABC, ST = I[:3 * M], I[3 * M + 1:]

E = [[0] * N for _ in range(N)]
for a, b, c in zip(*[iter(ABC)] * 3):
    E[a - 1][b - 1] = E[b - 1][a - 1] = c

E = floyd_warshall(E)

for i in range(N):
    for j in range(N):
        E[i][j] = (E[i][j] <= L)

E = floyd_warshall(E)

INF = float("inf")

for s, t in zip(*[iter(ST)] * 2):
    a = E[s - 1][t - 1] - 1
    print(-1 if a == INF else int(a))

Submission status: Accepted

Solution code:
from scipy.sparse.csgraph import floyd_warshall

N, M, L = map(int, input().split())
E = [[0] * N for _ in range(N)]
for _ in range(M):
    a, b, c = map(int, input().split())
    E[a - 1][b - 1] = E[b - 1][a - 1] = c

E = floyd_warshall(E)

for i in range(N):
    for j in range(N):
        E[i][j] = (E[i][j] <= L)

E = floyd_warshall(E)

INF = float("inf")

Q = int(input())
for _ in range(Q):
    s, t = map(int, input().split())
    a = E[s - 1][t - 1] - 1
    print(-1 if a == INF else int(a))

Submission status: Accepted

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


class Node(object):

  def __init__(self):
    self.fixed = False
    self.supply = 300
    self.tank = 0
    self.edges = []

  def __repr__(self):
    return str(self)

  def __str__(self):
    return '{}/{}({})'.format(self.supply, self.tank, int(self.fixed))


def main():
  n, m, tank = map(int, input().split())
  nodes = [Node() for _ in range(n)]

  for _ in range(m):
    a, b, c = map(int, input().split())

    nodes[a - 1].edges.append((nodes[b - 1], c))
    nodes[b - 1].edges.append((nodes[a - 1], c))

  queries = [list(map(int, input().split())) for _ in range(int(input()))]
  results = [[None] * len(nodes) for _ in range(len(nodes))]

  for start in range(len(nodes)):
    for node in nodes:
      node.fixed = False
      node.supply = 300
      node.tank = 0

    nodes[start].supply = 0
    nodes[start].tank = tank

    while True:
      targets = [n for n in nodes if not n.fixed ]

      if len(targets) == 0:
        break

      target = min(targets, key=lambda n: (n.supply, -n.tank))
      target.fixed = True

      for n, d in target.edges:
        if n.fixed or d > tank:
          continue

        if d > target.tank:
          new_supply = target.supply + 1
          new_tank = tank - d
        else:
          new_supply = target.supply
          new_tank = target.tank - d

        if (new_supply, -new_tank) < (n.supply, -n.tank):
          n.supply = new_supply
          n.tank = new_tank

    for end in range(len(nodes)):
      results[start][end] = nodes[end].supply

  for start, end in queries:
    if results[start - 1][end - 1] == 300:
      print(-1)
    else:
      print(results[start - 1][end - 1])


if __name__ == '__main__':
  main()