hihocoder 1654

http://hihocoder.com/problemset/problem/1654?sid=1249752

思路：广搜

import java.util.Arrays;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;
import java.util.Queue;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner cin = new Scanner(System.in);
        String str[] = new String[10];
        for(int i = 0;i<4;i++)
            str[i] = cin.next();
        Map<String, Integer>s = new HashMap<>();
        String tmp =str[0]+str[1]+str[2]+str[3];
        char [][]str1 = new char[10][10];
        if(check(tmp)==1)
            System.out.println(0);
        else {
                s.clear();
                s.put(tmp, 0);
                int [][]dir = {{1,0},{0,1},{-1,0},{0,-1}};
                 Queue<String>q = new LinkedList<>();
                 q.add(tmp);
                 boolean flag = false;
                 while(!q.isEmpty()){
                     tmp = q.poll();
                     //System.out.println(tmp.substring(0, 4)+"
"+tmp.substring(4, 8)+"
"+tmp.substring(8, 12)+"
"+tmp.substring(12, 16)+"  "+"num:"+s.get(tmp));
                     if(check(tmp)>=1){
                         System.out.println(s.get(tmp));
                         flag = true;
                         break;
                     }
                     str1[0] = tmp.substring(0, 4).toCharArray();
                     str1[1] = tmp.substring(4,8).toCharArray();
                     str1[2] = tmp.substring(8, 12).toCharArray();
                     str1[3] = tmp.substring(12, 16).toCharArray();
                     for(int i = 0;i<4;i++)
                         for(int j = 0;j<4;j++){
                             if(str1[i][j]!='O'){
                                 for(int k = 0;k<4;k++){
                                     int x = i+dir[k][0];
                                     int y = j+dir[k][1];
                                     if(x>=0&&x<4&&y>=0&&y<4&&str1[x][y]=='O'){
                                         str1[x][y] = str1[i][j];
                                         str1[i][j] = 'O';
                                         String tmp1="";
                                         for(int i1 = 0;i1<4;i1++)
                                             for(int j1=0;j1<4;j1++)
                                                 tmp1+=str1[i1][j1];
                                         //System.out.println("tmp1:"+tmp1);
                                         if(!s.containsKey(tmp1)){
                                             s.put(tmp1, s.get(tmp)+1);
                                             q.add(tmp1);
                                         }
                                         str1[i][j] = str1[x][y];
                                         str1[x][y] ='O';
                                     }
                                 }
                             }
                         }
                 }
                 if(!flag)
                     System.out.println(-1);
        }
    }
    
    public static int check(String x){
        for(int i = 0;i<16;i+=4){
            if(x.charAt(0+i)==x.charAt(1+i)&&x.charAt(1+i)==x.charAt(2+i)&&x.charAt(2+i)==x.charAt(3+i)&&x.charAt(0+i)!='O')
                return 1;
        }
        for(int i = 0;i<4;i++)
            if(x.charAt(i)==x.charAt(i+4)&&x.charAt(i)==x.charAt(i+8)&&x.charAt(i)==x.charAt(i+12)&&x.charAt(i)!='O')
                return 2;
        if(x.charAt(0)==x.charAt(5)&&x.charAt(0)==x.charAt(10)&&x.charAt(0)==x.charAt(15)&&x.charAt(0)!='O')
            return 3;

        if(x.charAt(3)==x.charAt(6)&&x.charAt(3)==x.charAt(9)&&x.charAt(3)==x.charAt(12)&&x.charAt(3)!='O')
            return 4;
        return 0;
    }
}