897. 最长公共子序列

#include<iostream>
using namespace std;

const int N = 1010;
char a[N], b[N];
int n, m;
int f[N][N];

int main(){
    cin >> n >> m;
    scanf("%s%s", a + 1, b + 1);

    for(int i = 1; i <= n; i ++)
        for(int j = 1; j <= m; j ++){
            f[i][j] = max(f[i - 1][j], f[i][j - 1]);
            if(a[i] == b[j]) f[i][j] = max(f[i - 1][j - 1] + 1, f[i][j]);
        }

    cout << f[n][m] << endl;
    return 0;
}