LeetCode——5. Longest Palindromic Substring

public class Solution {
public String longestPalindrome(String s) {
int len=s.length();
int leftIndex=0,rightIndex=0;
int maxLen=1;
if(s.length()==0){
return "";
}
//按下三角存储上三角
int[][] b=new int[len][];
for(int i=0;i<len;i++){
b[i]=new int[i+1];
}
//初始化对角线,b[i][j]=1表示s[j..i]是回文串，=0表示不是回文串
for(int i=0;i<len;i++){
b[i][i]=1;
}
for(int x=1,dis=1;x<len;x++,dis++){
for(int cur_x=x;cur_x<len;cur_x++){
int cur_y=cur_x-dis;
char leftChar=s.charAt(cur_y);
char rightChar=s.charAt(cur_x);

if(leftChar!=rightChar)
b[cur_x][cur_y]=0;
else{
if((cur_x-1 < cur_y+1) || b[cur_x-1][cur_y+1]==1){
//s[cur_y...cur_x]为回文串
b[cur_x][cur_y]=1;
int cur_len=cur_x-cur_y+1;
if(cur_len>maxLen){
maxLen=cur_len;
leftIndex=cur_y;
rightIndex=cur_x;
}
}
else
b[cur_x][cur_y]=0;
}
}
}
return s.substring(leftIndex, rightIndex+1);
}
}