E - 连连看 HDU - 1175 Java

​​题目连接​​

拿来练dfs了。细节较多。debug较多。

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;
import java.util.Set;
import java.util.TreeSet;
import java.util.Vector;

public class Main {
  static int n, m, x1, x2, y1, y2;
  static boolean vis[][] = new boolean[1005][1005];
  static int mp[][] = new int[1005][1005];
  static int flag;
  static void dfs(int x, int y, int turn, int dis) {
    if(flag == 1) {
      vis[x][y] = false;
      return ;
    }
  //  System.out.println(x + " " + y + " " + turn + " " + dis + " " + vis[x][y]);
    if(mp[x][y] != 0 || turn > 2 || x <= 0 || x > n || y <= 0 || y > m || vis[x][y])
    {
      return ;
    }
    if(x == x2 && y == y2) {
      flag = 1;
      vis[x][y] = false;
    //  System.out.println(1111111);
      return ;
    }
    vis[x][y] = true;
    if(x == x1 && y == y1) {
    dfs(x, y + 1, turn, 1);
    dfs(x + 1, y, turn, 2);
    dfs(x, y - 1, turn, 3);
    dfs(x - 1, y, turn, 4);
    }
    if(dis == 1) {
    dfs(x, y + 1, turn, 1);
    dfs(x + 1, y, turn + 1, 2);
    dfs(x, y - 1, turn + 1, 3);
    dfs(x - 1, y, turn + 1, 4);
    }
    if(dis == 2) {
    dfs(x + 1, y, turn, 2);
    dfs(x, y + 1, turn + 1, 1);
    dfs(x, y - 1, turn + 1, 3);
    dfs(x - 1, y, turn + 1, 4);
    }
    if(dis == 3) {
    dfs(x, y - 1, turn, 3); 
    dfs(x, y + 1, turn + 1, 1);
    dfs(x + 1, y, turn + 1, 2);
    dfs(x - 1, y, turn + 1, 4);
    }
    if(dis == 4) {
    dfs(x - 1, y, turn, 4);
    dfs(x, y + 1, turn + 1, 1);
    dfs(x + 1, y, turn + 1, 2);
    dfs(x, y - 1, turn + 1, 3);
    }
    vis[x][y] = false;
  }
  public static void main(String[] args) {
    Scanner cin = new Scanner(System.in);
    while(true) {
      n = cin.nextInt();
      m = cin.nextInt();
      if(n == 0 && m == 0)break;
      for(int i = 1;i <= n;i++)
        for(int j = 1;j <= m;j++) {
        mp[i][j] = cin.nextInt();
        vis[i][j] = false;
        }
      int q = cin.nextInt();
      for(int i = 0; i < q;i++) {
        x1 = cin.nextInt();
        y1 = cin.nextInt();
        x2 = cin.nextInt();
        y2 = cin.nextInt();
        flag = 0;
        if(mp[x1][y1] == mp[x2][y2] && mp[x2][y2] != 0) {
          int t1 = mp[x1][y1];
          int t2 = mp[x2][y2];
          mp[x1][y1] = 0;
          mp[x2][y2] = 0;
          dfs(x1, y1, 0, 1);
          mp[x1][y1] = t1;
          mp[x2][y2] = t2;
          if(flag == 1)System.out.println("YES");
          else System.out.println("NO");
        }else System.out.println("NO");
      }
    }
    
  }
}