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Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring.
O(n^2)
public class Solution {
public String longestPalindrome(String s) {
String maxString = "";
if(s.isEmpty() || s.length() == 1){
return s;
}
for(int i = 0; i < s.length() -1; i++){
String cur = helper(i, i, s);
if(cur.length() > maxString.length()){
maxString = cur;
}
cur = helper(i, i+1, s);
if(cur.length() > maxString.length()){
maxString = cur;
}
}
return maxString;
}
public String helper(int left, int right, String s){
while(left >= 0 && right < s.length() && s.charAt(left) == s.charAt(right)){
left --;
right ++;
}
return s.substring(left+1, right);
}
}
5. Longest Palindromic Substring
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原文地址：http://www.cnblogs.com/joannacode/p/5816570.html
