public static String longestPalindrome(String s) {
int length = s.length();
boolean[][] dp = new boolean[length][length];
//当前回文子串的最大长度
int maxLen = 1;
//最长回文子串的左角标
int left = 0;
//最长回文子串的右角标
int right = 0;
//先处理边界值
dp[length-1][length-1] = true;
for (int i = 0; i < length-1; i++) {
//对角线
dp[i][i] = true;
//次对角线
dp[i][i+1] = s.charAt(i)==s.charAt(i+1);
//判断次对角线中是否含有最终答案
if(dp[i][i+1]){
maxLen = 2;
left = i;
right = i+1;
}
}
for (int j = 2; j < length; j++) {
for (int i = 0; i <= j-2; i++) {
//当前两个字符是否相等
if(s.charAt(i)==s.charAt(j)){
//如果相等只需要取子串对应的值
dp[i][j] = dp[i+1][j-1];
}else {
//如果不相等，那么当前肯定不是回文子串
dp[i][j] = false;
}
//判断是否最长
if(dp[i][j] && j-i+1>maxLen){
maxLen = j-i+1;
left = i;
right = j;
}
}
}
return s.substring(left,right+1);
}