Problem: There is a staircase with N steps. Takahashi is now standing at the foot of the stairs, that is, on the 0-th step. He can climb up one or two steps at a time.  However, the treads of the a_1-th, a_2-th, a_3-th, \ldots, a_M-th steps are broken, so it is dangerous to set foot on those steps.  How many are there to climb up to the top step, that is, the N-th step, without setting foot on the broken steps? Find the count modulo 1\ 000\ 000\ 007.

Submission attempts (in order):
import sys
N, M = map(int, input().split())

a_list = [0] * M

for m in range(M):
    a_list[m] = int(input())

for m in range(M - 1):
    if a_list[m] + 1 == a_list[m + 1]:
        print(0)
        sys.exit()
    else:
        continue

range_list = [i for i in range(1, N + 1)]
new_list = [0] * (M + 1)

new_list[0] = [0] + range_list[0: a_list[0] - 1]
new_list[M] = range_list[a_list[M - 1]:]

if M - 1 >= 1:
    for m in range(1, M):
        new_list[m] = range_list[a_list[m - 1]: a_list[m] - 1]

MOD = 1000000007

def fib(n):
    dp_list = [0] * n
    dp_list[0] = 1
    if n == 1:
        return 1
    dp_list[1] = 2
    
    for i in range(2, n):
        dp_list[i] = dp_list[i - 1] + dp_list[i - 2]
    return dp_list[n - 1]
print(new_list)
count = 1
for item in new_list:
    if not item or len(item) == 1:
        continue
    else:
        count *= (fib(len(item) - 1) % MOD)
        count %= MOD
        #print(count)
print(count)

import sys
N, M = map(int, input().split())

a_list = [0] * M

for m in range(M):
    a_list[m] = int(input())

for m in range(M - 1):
    if a_list[m] + 1 == a_list[m + 1]:
        print(0)
        sys.exit()
    else:
        continue

range_list = [i for i in range(1, N + 1)]
new_list = [0] * (M + 1)

new_list[0] = range_list[0: a_list[0] - 1]
new_list[M] = range_list[a_list[M - 1]:]

if M - 1 >= 1:
    for m in range(1, M):
        new_list[m] = range_list[a_list[m - 1]: a_list[m] - 1]

MOD = 1000000007

def fib(n):
    dp_list = [0] * n
    dp_list[0] = 1
    dp_list[1] = 2
    
    for i in range(2, n):
        dp_list[i] = dp_list[i - 1] + dp_list[i - 2]
    return dp_list[n - 1]

count = 1
for item in new_list:
    if not item:
        continue
    else:
        count *= (fib(len(item) - 1) % MOD)
        count %= MOD
print(count)

import sys
N, M = map(int, input().split())

a_list = [0] * M

for m in range(M):
    a_list[m] = int(input())

for m in range(M - 1):
    if a_list[m] + 1 == a_list[m + 1]:
        print(0)
        sys.exit()
    else:
        continue

range_list = [i for i in range(1, N + 1)]
new_list = [0] * (M + 1)

new_list[0] = range_list[0: a_list[0] - 1]
new_list[M] = range_list[a_list[M - 1]:]

if M - 1 >= 1:
    for m in range(1, M):
        new_list[m] = range_list[a_list[m - 1]: a_list[m] - 1]

MOD = 1000000007

def fib(n):
    dp_list = [0] * n
    dp_list[0] = 1
    dp_list[1] = 2
    
    for i in range(2, n):
        dp_list[i] = dp_list[i - 1] + dp_list[i - 2]
    return dp_list[n - 1]

count = 1
for item in new_list:
    if not item:
        continue
    else:
        count *= (fib(len(item) - 1) % MOD)
        count %= MOD
print(count)

import sys
N, M = map(int, input().split())

MOD = 1000000007

def fib(n):
    dp_list = [0] * n
    dp_list[0] = 1
    if n == 1:
        return 1
    dp_list[1] = 2
    
    for i in range(2, n):
        dp_list[i] = dp_list[i - 1] + dp_list[i - 2]
    return dp_list[n - 1]

if M == 0:
    print(fib(N) % MOD)
    sys.exit()

a_list = [0] * M

for m in range(M):
    a_list[m] = int(input())

for m in range(M - 1):
    if a_list[m] + 1 == a_list[m + 1]:
        print(0)
        sys.exit()
    else:
        continue

range_list = [i for i in range(1, N + 1)]
new_list = [0] * (M + 1)


new_list[0] = [0] + range_list[0: a_list[0] - 1]
new_list[M] = range_list[a_list[M - 1]:]

if M - 1 >= 1:
    for m in range(1, M):
        new_list[m] = range_list[a_list[m - 1]: a_list[m] - 1]

count = 1
for item in new_list:
    if not item or len(item) == 1:
        continue
    else:
        count *= (fib(len(item) - 1) % MOD)
        count %= MOD
        #print(count)
print(count)

Verdicts: Runtime Error

Runtime Error

Runtime Error

Accepted