最长公共子序列 最长公共子串

公共子串和公共子序列是不同的

 

class maxstr():
    def LCS(self,string1,string2):
        len1 = len(string1)
        len2 = len(string2)
        res = [[0 for i in range(len1+1)] for j in range(len2+1)]
        for i in range(1,len2+1):
            for j in range(1,len1+1):
                if string2[i-1] == string1[j-1]:
                    res[i][j] = res[i-1][j-1]+1
                else:
                    res[i][j] = max(res[i-1][j],res[i][j-1])
        return res,res[-1][-1]
aa=maxstr()
print(aa.LCS("helloworld","loop"))

 

class maxstr():
    def LCstring(self,string1,string2):
        len1 = len(string1)
        len2 = len(string2)
        res = [[0 for i in range(len1+1)] for j in range(len2+1)]
        result = 0
        for i in range(1,len2+1):
            for j in range(1,len1+1):
                if string2[i-1] == string1[j-1]:
                    res[i][j] = res[i-1][j-1]+1
                    result = max(result,res[i][j])  
        print(res)
        return result
aa=maxstr()
print(aa.LCstring("helloworld","loop"))

[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],

[0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0],

[0, 0, 0, 0, 0, 2, 0, 1, 0, 0, 0],

[0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0],

[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]

2