5.最长回文子串

• 一、题目描述
• 二、示例
• 三、难度
• 四、代码
• • Java版

给你一个字符串 s，找到 s 中最长的回文子串

中等

从中⼼向两端扩散

class Solution {
    public String palindrome(String s,int left , int right) {
        while (left >= 0 && right < s.length() && s.charAt(left) == s.charAt(right)) {
            --left;
            ++right;
        }
        return s.substring(left+1,right);
    }

    public String longestPalindrome(String s) {
        if(s.length() < 2) return s;
        int left = 0, right = 0;
        String str = "";
        for (int i = 0; i < s.length(); ++i) {
       		
            String oddStr = palindrome(s,i,i);
            String evenStr = palindrome(s,i,i+1);


            str = str.length()>oddStr.length()?str:oddStr;
            str = str.length()>evenStr.length()?str:evenStr;
        }
        return str;
    }
}