java-JD11_回文

java-JD11 回文

import java.util.Scanner;

/**
 * JD11 回文
 * @author d3y1
 */
public class Main {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);

        while(in.hasNext()){
            solution1(in);
            solution2(in);
        }
    }

    /**
     * 模拟法
     * @param in
     */
    private static void solution1(Scanner in){
        String s = in.nextLine();
        int len = s.length();

        int result = 0;
        for(int i=0; i<len; i++){
            if(isPalindrome(s.substring(i))){
                result = len+i;
                break;
            }
        }

        System.out.println(result);
    }

    /**
     * 模拟法
     * @param in
     */
    private static void solution2(Scanner in){
        String s = in.nextLine();
        int len = s.length();

        int result;
        int resultOdd = Integer.MAX_VALUE;
        int resultEven = Integer.MAX_VALUE;
        if(checkPalindrome(s)){
            result = len;
        }else{
            int index = len/2;
            boolean found = false;
            for(int i=index; i<len; i++){
                // odd
                for(int left=i-1,right=i+1; 0<=left&&right<=len; left--,right++){
                    if(right == len){
                        resultOdd = len+left+1;
                        found = true;
                        break;
                    }else if(s.charAt(left) == s.charAt(right)){
                        continue;
                    }else{
                        break;
                    }
                }

                // even
                for(int left=i,right=i+1; 0<=left&&right<=len; left--,right++){
                    if(right == len){
                        resultEven = len+left+1;
                        found = true;
                        break;
                    }else if(s.charAt(left) == s.charAt(right)){
                        continue;
                    }else{
                        break;
                    }
                }

                if(found){
                    break;
                }
            }

            result = Math.min(resultOdd, resultEven);
        }

        System.out.println(result);
    }

    /**
     * 是否回文串
     * @param s
     * @return
     */
    private static boolean isPalindrome(String s){
        StringBuilder sb = new StringBuilder(s);
        return s.equals(sb.reverse().toString());
    }

    /**
     * 是否回文串
     * @param s
     * @return
     */
    private static boolean checkPalindrome(String s){
        int left = 0;
        int right = s.length()-1;
        while(left < right){
            if(s.charAt(left) != s.charAt(right)){
                return false;
            }
            left++;
            right--;
        }
        
        return true;
    }
}