题解 | #最长回文子串#

import java.util.*;

public class Main {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        while(in.hasNext()){
            char[] arr = in.nextLine().toCharArray();
            //以i或者(i,i+1)位置的节点为中间节点，向两边辐射
            int max = 0;
            for(int i = 0; i < arr.length; i++){
                int t = i;
                int i1 = t;
                int j1 = t + 1;
                int i2 = t;
                int j2 = t + 1;

                while(i1 > 0 && j1 < arr.length && arr[i1 - 1] == arr[j1]){
                    i1--;
                    j1++;
                }

                while(i2 >= 0 && j2 < arr.length && arr[i2] == arr[j2]){
                    i2--;
                    j2++;
                }
                max = Math.max(max, Math.max(j1 - i1, j2 - i2 - 1));
                i = t;
            }
            System.out.println(max);
        }
    }
}