Buggy python submission (verdict: Time Limit Exceeded):
import sys
sys.setrecursionlimit(1000000000)

def main():
    N,M = map(int,input().split())
    e = [[] for i in range(N)]
    t = 0
    a = []
    for i in range(M):
        r,l,d = map(int,input().split())
        e[r-1].append([l-1,d])
        e[l-1].append([r-1,-d])
        a.append(r-1)
        a.append(l-1)
        t = r-1

    col = [ float("inf") for i in range(N) ]
    def dfs(i,c):
        for node in e[i]:
            if col[node[0]] == float("inf"):
                col[node[0]] = c + node[1]
                dfs(node[0],c+node[1])
            elif col[node[0]] != c + node[1]:
                print("No")
                exit()


    dfs(t,0)
    a = list(set(a))
    for i in a:
        if col[i] == float("inf"):
            dfs(i,0)


    print("Yes")


if __name__ == '__main__':
    main()


Fixed submission:
import sys
sys.setrecursionlimit(100000000)

def main():
    N,M = map(int,input().split())
    e = [[] for i in range(N)]
    t = 0
    a = []
    for i in range(M):
        r,l,d = map(int,input().split())
        e[r-1].append([l-1,d])
        e[l-1].append([r-1,-d])
        a.append(r-1)
        a.append(l-1)
        t = r-1

    col = [ float("inf") for i in range(N) ]
    def dfs(i,c):

        for node in e[i]:
            if col[node[0]] == float("inf"):
                col[node[0]] = c + node[1]
                dfs(node[0],c+node[1])
            elif col[node[0]] != c + node[1]:
                print("No")
                exit()


    dfs(t,0)
    a = list(set(a))
    for i in a:
        if col[i] == float("inf"):
            dfs(i,0)


    print("Yes")


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
sys.setrecursionlimit(1000000000)

def main():
    N,M = map(int,input().split())
    e = [[] for i in range(N)]
    t = 0
    a = []
    for i in range(M):
        r,l,d = map(int,input().split())
        e[r-1].append([l-1,d])
        e[l-1].append([r-1,-d])
        a.append(r-1)
        a.append(l-1)
        t = r-1

    col = [ float("inf") for i in range(N) ]
    def dfs(i,c):
        for node in e[i]:
            if col[node[0]] == float("inf"):
                col[node[0]] = c + node[1]
                dfs(node[0],c+node[1])
            elif col[node[0]] != c + node[1]:
                print("No")
                exit()


    dfs(t,0)
    a = list(set(a))
    for i in a:
        if col[i] == float("inf"):
            dfs(i,0)


    print("Yes")


if __name__ == '__main__':
    main()


Fixed submission:
import sys
sys.setrecursionlimit(100000000)

def main():
    N,M = map(int,input().split())
    e = [[] for i in range(N)]
    t = 0
    a = []
    for i in range(M):
        r,l,d = map(int,input().split())
        e[r-1].append([l-1,d])
        e[l-1].append([r-1,-d])
        a.append(r-1)
        a.append(l-1)
        t = r-1

    col = [ float("inf") for i in range(N) ]
    def dfs(i,c):

        for node in e[i]:
            if col[node[0]] == float("inf"):
                col[node[0]] = c + node[1]
                dfs(node[0],c+node[1])
            elif col[node[0]] != c + node[1]:
                print("No")
                exit()


    dfs(t,0)
    a = list(set(a))
    for i in a:
        if col[i] == float("inf"):
            dfs(i,0)


    print("Yes")


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
sys.setrecursionlimit(100000000)

def main():
    N,M = map(int,input().split())
    e = [[] for i in range(N)]
    t = 0
    a = []
    for i in range(M):
        r,l,d = map(int,input().split())
        e[r-1].append([l-1,d])
        e[l-1].append([r-1,-d])
        a.append(r-1)
        a.append(l-1)
        t = r-1

    col = [ float("inf") for i in range(N) ]
    def dfs(i,c):
        for node in e[i]:
            if col[node[0]] == float("inf"):
                col[node[0]] = c + node[1]
                dfs(node[0],c+node[1])
            elif col[node[0]] != c + node[1]:
                print("No")
                exit()


    dfs(t,0)
    a = list(set(a))
    for i in a:
        if col[i] == float("inf"):
            dfs(i,0)


    print("Yes")


if __name__ == '__main__':
    main()


Fixed submission:
import sys
sys.setrecursionlimit(100000000)

def main():
    N,M = map(int,input().split())
    e = [[] for i in range(N)]
    t = 0
    a = []
    for i in range(M):
        r,l,d = map(int,input().split())
        e[r-1].append([l-1,d])
        e[l-1].append([r-1,-d])
        a.append(r-1)
        a.append(l-1)
        t = r-1

    col = [ float("inf") for i in range(N) ]
    def dfs(i,c):

        for node in e[i]:
            if col[node[0]] == float("inf"):
                col[node[0]] = c + node[1]
                dfs(node[0],c+node[1])
            elif col[node[0]] != c + node[1]:
                print("No")
                exit()


    dfs(t,0)
    a = list(set(a))
    for i in a:
        if col[i] == float("inf"):
            dfs(i,0)


    print("Yes")


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
sys.setrecursionlimit(100000000)

def main():
    N,M = map(int,input().split())
    e = [[] for i in range(N)]
    t = 0
    a = []
    for i in range(M):
        r,l,d = map(int,input().split())
        e[r-1].append([l-1,d])
        e[l-1].append([r-1,-d])
        a.append(r-1)
        a.append(l-1)
        t = r-1

    col = [ float("inf") for i in range(N) ]
    def dfs(i,c):
        for node in e[i]:
            if col[node[0]] == float("inf"):
                col[node[0]] = c + node[1]
                dfs(node[0],c+node[1])
            elif col[node[0]] != c + node[1]:
                print("No")
                exit()


    dfs(t,0)
    a = list(set(a))
    for i in a:
        if col[i] == float("inf"):
            dfs(i,0)


    print("Yes")


if __name__ == '__main__':
    main()


Fixed submission:
import sys
sys.setrecursionlimit(100000000)

def main():
    N,M = map(int,input().split())
    e = [[] for i in range(N)]
    t = 0
    a = []
    for i in range(M):
        r,l,d = map(int,input().split())
        e[r-1].append([l-1,d])
        e[l-1].append([r-1,-d])
        a.append(r-1)
        a.append(l-1)
        t = r-1

    col = [ float("inf") for i in range(N) ]
    def dfs(i,c):

        for node in e[i]:
            if col[node[0]] == float("inf"):
                col[node[0]] = c + node[1]
                dfs(node[0],c+node[1])
            elif col[node[0]] != c + node[1]:
                print("No")
                exit()


    dfs(t,0)
    a = list(set(a))
    for i in a:
        if col[i] == float("inf"):
            dfs(i,0)


    print("Yes")


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
sys.setrecursionlimit(100000000)
N,M = map(int,input().split())
e = [[] for i in range(N)]
t = 0
a = []
for i in range(M):
    r,l,d = map(int,input().split())
    e[r-1].append([l-1,d])
    e[l-1].append([r-1,-d])
    a.append(r-1)
    a.append(l-1)
    t = r-1

col = [ float("inf") for i in range(N) ]
def dfs(i,c):

    for node in e[i]:
        if col[node[0]] == float("inf"):
            col[node[0]] = c + node[1]
            dfs(node[0],c+node[1])
        elif col[node[0]] != c + node[1]:
            print("No")
            exit()


dfs(t,0)
a = list(set(a))
for i in a:
    if col[i] == float("inf"):
        dfs(i,0)


print("Yes")


Fixed submission:
import sys
sys.setrecursionlimit(100000000)

def main():
    N,M = map(int,input().split())
    e = [[] for i in range(N)]
    t = 0
    a = []
    for i in range(M):
        r,l,d = map(int,input().split())
        e[r-1].append([l-1,d])
        e[l-1].append([r-1,-d])
        a.append(r-1)
        a.append(l-1)
        t = r-1

    col = [ float("inf") for i in range(N) ]
    def dfs(i,c):

        for node in e[i]:
            if col[node[0]] == float("inf"):
                col[node[0]] = c + node[1]
                dfs(node[0],c+node[1])
            elif col[node[0]] != c + node[1]:
                print("No")
                exit()


    dfs(t,0)
    a = list(set(a))
    for i in a:
        if col[i] == float("inf"):
            dfs(i,0)


    print("Yes")


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
N,M = map(int,input().split())
e = [[] for i in range(N)]
t = 0
for i in range(M):
    r,l,d = map(int,input().split())
    e[r-1].append([l-1,d])
    e[l-1].append([r-1,-d])
    t = r-1

col = [ -1 for i in range(N) ]
def dfs(i,c):

    for node in e[i]:
        if col[node[0]] == -1:
            col[node[0]] = c + node[1]
            dfs(node[0],c+node[1])
        elif col[node[0]] != c + node[1]:
            print("No")
            exit()

dfs(t,0)

print("Yes")


Fixed submission:
import sys
sys.setrecursionlimit(100000000)

def main():
    N,M = map(int,input().split())
    e = [[] for i in range(N)]
    t = 0
    a = []
    for i in range(M):
        r,l,d = map(int,input().split())
        e[r-1].append([l-1,d])
        e[l-1].append([r-1,-d])
        a.append(r-1)
        a.append(l-1)
        t = r-1

    col = [ float("inf") for i in range(N) ]
    def dfs(i,c):

        for node in e[i]:
            if col[node[0]] == float("inf"):
                col[node[0]] = c + node[1]
                dfs(node[0],c+node[1])
            elif col[node[0]] != c + node[1]:
                print("No")
                exit()


    dfs(t,0)
    a = list(set(a))
    for i in a:
        if col[i] == float("inf"):
            dfs(i,0)


    print("Yes")


if __name__ == '__main__':
    main()