Buggy python submission (verdict: Time Limit Exceeded):
import sys

input = sys.stdin.readline

def main():
    ans = 0
    mod = (10**9)+7
    n = int(input())
    a = list(map(int, input().split()))
    for i in range(n):
        a[i] %= mod
    for i in range(n-1):
        for j in range(i+1, n):
            ans +=  a[i]*a[j]
    print(ans%mod)

if __name__ == '__main__':
    main()

Fixed submission:
import sys

input = sys.stdin.readline

def main():
    ans = 0
    mod = (10**9)+7
    n = int(input())
    a = list(map(int, input().split()))
    suma = sum(a)
    for i in range(n-1):
        suma -= a[i]
        ans += a[i]*suma
    print(ans%mod)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys

input = sys.stdin.readline

def main():
    ans = 0
    mod = (10**9)+7
    n = int(input())
    a = list(map(int, input().split()))
    for i in a:
        i %= mod
    for i in range(n-1):
        for j in range(i+1, n):
            ans +=  a[i]*a[j]
    print(ans%mod)

if __name__ == '__main__':
    main()

Fixed submission:
import sys

input = sys.stdin.readline

def main():
    ans = 0
    mod = (10**9)+7
    n = int(input())
    a = list(map(int, input().split()))
    suma = sum(a)
    for i in range(n-1):
        suma -= a[i]
        ans += a[i]*suma
    print(ans%mod)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys

input = sys.stdin.readline

def main():
    ans = 0
    mod = (10**9)+7
    n = int(input())
    a = list(map(int, input().split()))
    for i in range(n-1):
        for j in range(i+1, n):
           ans += (a[i]%mod*a[j]%mod)%mod
    print(ans%mod)

if __name__ == '__main__':
    main()

Fixed submission:
import sys

input = sys.stdin.readline

def main():
    ans = 0
    mod = (10**9)+7
    n = int(input())
    a = list(map(int, input().split()))
    suma = sum(a)
    for i in range(n-1):
        suma -= a[i]
        ans += a[i]*suma
    print(ans%mod)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys

input = sys.stdin.readline

def main():
    ans = 0
    mod = (10**9)+7
    n = int(input())
    a = list(map(int, input().split()))
    for i in range(n-1):
        for j in range(i+1, n):
           ans += (a[i]*a[j])%mod
    print(ans%mod)

if __name__ == '__main__':
    main()

Fixed submission:
import sys

input = sys.stdin.readline

def main():
    ans = 0
    mod = (10**9)+7
    n = int(input())
    a = list(map(int, input().split()))
    suma = sum(a)
    for i in range(n-1):
        suma -= a[i]
        ans += a[i]*suma
    print(ans%mod)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys

input = sys.stdin.readline

def main():
    ans = 0
    mod = (10**9)+7
    n = int(input())
    a = list(map(int, input().split()))
    for i in range(n):
        for j in range(i, n):
           ans += a[i]*a[j]
    for i in a:
        ans -= i**2 
    print(ans%mod)

if __name__ == '__main__':
    main()

Fixed submission:
import sys

input = sys.stdin.readline

def main():
    ans = 0
    mod = (10**9)+7
    n = int(input())
    a = list(map(int, input().split()))
    suma = sum(a)
    for i in range(n-1):
        suma -= a[i]
        ans += a[i]*suma
    print(ans%mod)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys

input = sys.stdin.readline

def main():
    ans = 0
    mod = (10**9)+7
    n = int(input())
    a = list(map(int, input().split()))
    for i in range(n-1):
        for j in range(i+1, n):
            ans += a[i]*a[j]
    print(ans%mod)

if __name__ == '__main__':
    main()

Fixed submission:
import sys

input = sys.stdin.readline

def main():
    ans = 0
    mod = (10**9)+7
    n = int(input())
    a = list(map(int, input().split()))
    suma = sum(a)
    for i in range(n-1):
        suma -= a[i]
        ans += a[i]*suma
    print(ans%mod)

if __name__ == '__main__':
    main()