C++，代码易懂易写才是最让人舒服

#include <bits/stdc++.h>
using namespace std;
int LCS(const string& str1,const string& str2) {
        // write code here
        int m = str1.size();
        int n = str2.size();
        // dp[i][j] str1前i个字符和str2前j个字符（以其为尾字符）的最长公共子串长度
        int dp[m+1][n+1];
        int maxlen = 0;
        //base case
        for(int i = 0; i <= m; ++i) dp[i][0] = 0;
        for(int j = 0; j <= n; ++j) dp[0][j] = 0;
        for(int i = 1; i <= m; ++i) {
            for(int j = 1; j <= n; ++j) {
                if(str1[i-1] == str2[j-1]) dp[i][j] = dp[i-1][j-1] + 1;
                else dp[i][j] = 0;
                if(dp[i][j] > maxlen) {
                    maxlen = dp[i][j];
                }
            }
        }
        return maxlen;
}
int main(){
    string s1,s2;
    cin>>s1>>s2;
    cout<<LCS(s1,s2);
}