【试题 基础练习 完美的代价】回文字符串特殊处理

import java.io.BufferedWriter;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.*;

public class Main {
    public  static  void main(String [] args){
        Scanner sc =new Scanner(System.in);
        int n=sc.nextInt();
       String str = sc.next();
       char []ch=str.toCharArray();
       int num[]=new int[26];
       for(int i=0;i<n;i++){
           num[ch[i]-‘a‘]++;
       }
       int count=0;
       for(int i=0;i<26;i++)
           if(num[i]%2!=0)
               count++;
       if(count>=2) System.out.println("Impossible");
       else System.out.println(getCount(str));
   }
   static int getCount(String str){
        if(str.length()==1||str.length()==2) return 0;

        int temp = str.lastIndexOf(str.charAt(0));
        if(temp==0){
            return str.length()/2+getCount(str.substring(1,str.length()));///等于本身也就是说此字符是放在中间的
        }else{
            StringBuilder stringBuilder = new StringBuilder(str);
            stringBuilder.deleteCharAt(temp);///移除找到的回文字符
            stringBuilder.deleteCharAt(0);
            return str.length()-temp-1+getCount(stringBuilder.toString());
        }
   }
}