题解 | #最长回文子串#

动态规划，每次通过长度去递推
public class Solution {
    public int getLongestPalindrome(String A) {
        int res = 1;
        int n = A.length();
        char[] a = A.toCharArray();
        boolean[][] f = new boolean[n][n];

        // 不能直接双重for循环，得通过长度去循环
        for (int len = 0; len < n; len++) {
            for (int k = 0; k < n - len; k++) {
                int i = k;
                int j = k + len;

                if (a[i] == a[j]) {
                    if (i == j || i + 1 == j) f[i][j] = true;
                    else f[i][j] = f[i + 1][j - 1];
                    if (f[i][j]) res = Math.max(res, j - i + 1);
                }
            }
        }
        return res;
    }
}