Buggy python submission (verdict: Runtime Error):
def main():
    num = int(input())
    for i in range(num):
        X = " " + input()
        Y = " " + input()
        lx = len(X)
        ly = len(Y)
        max = 0
        XY = [[0] * ly for i in range(lx)]
        for j in range(1,lx):
            for k in range(1,ly):
                if X[j] == Y[k]:
                    XY[j][k] = XY[j-1][k-1] + 1
                elif XY[j-1][k] > XY[j][k-1]:
                    XY[j][k] = XY[j-1][k]
                else:
                    XY[j][k] = XY[j][k-1]
                if max < XY[j][k]:
                    max = XY[j][k]
        print(max)
 f __name__ == '__main__':
    main()

Fixed submission:
def main():
    num = int(input())
    A = []
    for i in range(num):
        X = input()
        Y = " " + input()
        lx = len(X)
        ly = len(Y)
        T = [0] * ly
        for j in range(lx):
            xj = X[j]
            C = T[:]
            for k in range(1,ly):
                k1 = k-1
                if xj == Y[k]:
                    T[k] = C[k1] + 1
                elif T[k] < T[k1]:
                    T[k] = T[k1]
        print(T[k])
if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
def main():
    num = int(input())
    for i in range(num):
        X = " " + input()
        Y = " " + input()
        lx = len(X)
        ly = len(Y)
        max = 0
        XY = [[0] * ly for i in range(lx)]
        for j in range(1,lx):
            for k in range(1,ly):
                if X[j] == Y[k]:
                    XY[j][k] = XY[j-1][k-1] + 1
                elif XY[j-1][k] > XY[j][k-1]:
                    XY[j][k] = XY[j-1][k]
                else:
                    XY[j][k] = XY[j][k-1]
                if max < XY[j][k]:
                    max = XY[j][k]
        print(max)

if __name__ == '__main__':
    main()

Fixed submission:
def main():
    num = int(input())
    A = []
    for i in range(num):
        X = input()
        Y = " " + input()
        lx = len(X)
        ly = len(Y)
        T = [0] * ly
        for j in range(lx):
            xj = X[j]
            C = T[:]
            for k in range(1,ly):
                k1 = k-1
                if xj == Y[k]:
                    T[k] = C[k1] + 1
                elif T[k] < T[k1]:
                    T[k] = T[k1]
        print(T[k])
if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
def lcs1d(X,Y):
    lx = len(X)
    ly = len(Y)
    T = [0] * ly
    for j in range(1,lx):
        C = T[:]
        for k in range(1,ly):
            k1 = k-1
            if X[j] == Y[k]:
                T[k] = C[k1] + 1
            elif C[k] > T[k1]:
                T[k] = C[k]
            else:
                T[k] = T[k1]
    return T[k]

def main():
    """ ????????? """
    num = int(input())
    for i in range(num):
        X = " " + input()
        Y = " " + input()
        max = lcs1d(X,Y)
        print(max)

if __name__ == '__main__':
    main()

Fixed submission:
def main():
    num = int(input())
    A = []
    for i in range(num):
        X = input()
        Y = " " + input()
        lx = len(X)
        ly = len(Y)
        T = [0] * ly
        for j in range(lx):
            xj = X[j]
            C = T[:]
            for k in range(1,ly):
                k1 = k-1
                if xj == Y[k]:
                    T[k] = C[k1] + 1
                elif T[k] < T[k1]:
                    T[k] = T[k1]
        print(T[k])
if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
num = int(input())
for i in range(num):
    X = " " + input()
    Y = " " + input()
    lx = len(X)
    ly = len(Y)
    T = [0] * ly
    for j in range(1,lx):
        C = T[:]
        for k in range(1,ly):
            k1 = k-1
            if X[j] == Y[k]:
                T[k] = C[k1] + 1
            elif C[k] > T[k1]:
                T[k] = C[k]
            else:
                T[k] = T[k1]
    print(T[k])

Fixed submission:
def main():
    num = int(input())
    A = []
    for i in range(num):
        X = input()
        Y = " " + input()
        lx = len(X)
        ly = len(Y)
        T = [0] * ly
        for j in range(lx):
            xj = X[j]
            C = T[:]
            for k in range(1,ly):
                k1 = k-1
                if xj == Y[k]:
                    T[k] = C[k1] + 1
                elif T[k] < T[k1]:
                    T[k] = T[k1]
        print(T[k])
if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
def main():
    num = int(input())
    for i in range(num):
        X = " " + input()
        Y = " " + input()
        lx = len(X)
        ly = len(Y)
        T = [0] * ly
        for j in range(1,lx):
            C = T[:]
            for k in range(1,ly):
                k1 = k-1
                if X[j] == Y[k]:
                    T[k] = C[k1] + 1
                elif C[k] > T[k1]:
                    T[k] = C[k]
                else:
                    T[k] = T[k1]
        print(T[k])

if __name__ == '__main__':
    main()

Fixed submission:
def main():
    num = int(input())
    A = []
    for i in range(num):
        X = input()
        Y = " " + input()
        lx = len(X)
        ly = len(Y)
        T = [0] * ly
        for j in range(lx):
            xj = X[j]
            C = T[:]
            for k in range(1,ly):
                k1 = k-1
                if xj == Y[k]:
                    T[k] = C[k1] + 1
                elif T[k] < T[k1]:
                    T[k] = T[k1]
        print(T[k])
if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
def main():
    num = int(input())
    for i in range(num):
        X = " " + input()
        Y = " " + input()
        lx = len(X)
        ly = len(Y)
        T = [0] * ly
        for j in range(1,lx):
            C = T[:]
            for k in range(1,ly):
                k1 = k-1
                if X[j] == Y[k]:
                    T[k] = C[k1] + 1
                elif C[k] < T[k1]:
                    T[k] = T[k1]
        print(T[k])

if __name__ == '__main__':
    main()

Fixed submission:
def main():
    num = int(input())
    A = []
    for i in range(num):
        X = input()
        Y = " " + input()
        lx = len(X)
        ly = len(Y)
        T = [0] * ly
        for j in range(lx):
            xj = X[j]
            C = T[:]
            for k in range(1,ly):
                k1 = k-1
                if xj == Y[k]:
                    T[k] = C[k1] + 1
                elif T[k] < T[k1]:
                    T[k] = T[k1]
        print(T[k])
if __name__ == '__main__':
    main()