题解 | 最长回文子序列

#include <bits/stdc++.h>
using namespace std;

int main() {
    string s;
    cin >> s;
    int n = (int)s.size();
    vector<vector<int>> dp(n, vector<int>(n, 0));
    for (int i = n - 1; i >= 0; --i) {
        dp[i][i] = 1;
        for (int j = i + 1; j < n; ++j) {
            if (s[i] == s[j]) dp[i][j] = dp[i + 1][j - 1] + 2;
            else dp[i][j] = max(dp[i + 1][j], dp[i][j - 1]);
        }
    }
    cout << dp[0][n - 1] << '\n';
    return 0;
}