题解 | #DNA序列#

不知道为什么定义要放在前面

import java.util.*;
public class Main{
    static boolean[] visit = new boolean[4];
    static int[] nums = new int[4];
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        
        while(scan.hasNext()){
            
            String ss = scan.nextLine();
            String[] strs = ss.split(" ");
            for(int i = 0; i<4; i++){
                nums[i] = Integer.parseInt(strs[i]);
            }
            
            System.out.println(dfs(0,0));
        }
    }
    
    public static boolean dfs(int k, float sum){
        if(k == 4 && sum == 24){
            return true;
        }
        for(int i = 0; i<4; i++){
            if(visit[i] == false){
                visit[i] = true;
                if(dfs(k+1, sum+nums[i])||
                   dfs(k+1, sum-nums[i])||
                   dfs(k+1, sum*nums[i])||
                   dfs(k+1, sum/nums[i])){
                    return true;
               }
                visit[i] = false;
            }

        }
        return false;
    }
}