题解 | #最长公共子串#C++动态规划

动态规划：

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;

string get_str(string& s1, string& s2) {
    if(s1.size() > s2.size()) swap(s1, s2);
    int len1 = s1.size(), len2 = s2.size();
    vector<vector<int>> vv(len1 + 1, vector<int>(len2 + 1, 0));
    int max_size = 0, start;
    for(int i = 1; i <= len1; i++) {
        for(int j = 1; j <= len2; j++) {
            if(s1[i - 1] == s2[j - 1]) vv[i][j] = vv[i - 1][j - 1] + 1;
            if(vv[i][j] > max_size) {
                max_size = vv[i][j]; 
                start = i - max_size;
            }
        }
    }
    if(max_size == 0) return "ERROR";
    return s1.substr(start, max_size);
}

int main() 
{
    string s1, s2;
    while(cin >> s1 >> s2) {
        string res = get_str(s1, s2);
        if(res == "ERROR") cout << -1 << endl;
        else cout << res << endl;
    }
    return 0;
}