Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000.
Example 1:
Input: "babad"
Output: "bab"
Note: "aba" is also a valid answer.
Example 2:
Input: "cbbd"
Output: "bb"
class Solution {
public String longestPalindrome(String s) {
if(s==null || s.isEmpty()) return "";
if(s.length() == 1) {
return s;
}
String res = s.substring(0, 1);
for(int i=0;i<s.length();i++) {
String tmp = findPalindrome(s,i,i);
if(tmp.length() > res.length()) {
res = tmp;
}
tmp = findPalindrome(s,i,i+1);
if(tmp.length() > res.length()) {
res = tmp;
}
}
return res;
}
/**
* 分为aba形式的回文数 以及aa形式的回文数
* @param s
* @param index
* @return
*/
public String findPalindrome(String s,int index,int index2) {
int begin= index;
int resIndex =index2;
while (begin >= 0 && resIndex < s.length()) {
if (s.charAt(begin) == s.charAt(resIndex)) {
begin--;
resIndex++;
}else {
break;
}
}
return s.substring(begin+1, resIndex);
}
}