Steward

分享是一種喜悅、更是一種幸福

程式語言 - LeetCode - C++ - 516. Longest Palindromic Subsequence

---

題目：


方法：

    b b b a b
b [ 1 2 3 3 4 ]
b [ 0 1 2 2 3 ]
b [ 0 0 1 1 3 ]
a [ 0 0 0 1 1 ]
b [ 0 0 0 0 1 ]

解答：

class Solution {
public:
    int longestPalindromeSubseq(string s) {
        int n = s.size();
        vector<vector<int>> dp(n + 1, vector<int>(n + 1, 0));

        for (int i = 0; i < n; ++i) {
            dp[i][i] = 1;
        }

        for (int i = n - 1; i >= 0; --i) {
            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]);
                }
            }
        }

        return dp[0][n - 1];
    }
};