最长公共子串

LintCode题目地址

转移方程 f[i][j] = f[i - 1][j - 1] + 1

image

def longestCommonSubstring(self, A, B):
        # write your code here
        n = len(A)
        m = len(B)
        
        if n == 0 or m == 0:
            return 0
        
        f = [[0 for col in range(m)] for row in range(n)]
        
        maxsub = 0
        for i in range(n):
            f[i][0] = 0
            if A[i] == B[0]:
                f[i][0] = 1
                maxsub = 1
        for j in range(1,m):
            f[0][j] = 0
            if A[0] == B[j]:
                f[0][j] = 1
                maxsub = 1
                
        for i in range(1,n):
            for j in range(1,m):
                if A[i] == B[j]:
                    f[i][j] = f[i-1][j-1]+1
                else:
                    f[i][j] = 0
                
                maxsub = max(maxsub, f[i][j])
        
        return maxsub