飞行员兄弟Java

暴力枚举，就是太慢了，得四秒多

java样例

import java.util.*;
public class Main {
    static char[][] g = new char[4][4];
    static char[][] backup   = new char[4][4];
    static List<String> list = new ArrayList<>();
    static List<String> temp = new ArrayList<>();
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        for(int i=0;i<4;i++) {
            g[i]=sc.nextLine().toCharArray();
            backup[i]=Arrays.copyOf(g[i], 4);
        }

        //枚举2的16次方中方案
        int minStep = Integer.MAX_VALUE;
        for(int op=0;op<(1<<16);op++) {
            //每种方案的步骤数
            int step = 0;
            for(int i=0;i<16;i++) {
                if((op>>i&1)==1) {
                    int x = i/4;
                    int y = i%4;
                    temp.add((x+1)+" "+(y+1));
                    step++;
                    turn(x,y);
                }
            }

            boolean flag = false;
            for(int i=0;i<4;i++) {
                for(int j=0;j<4;j++) {
                    if(g[i][j]=='+') {
                        flag = true;
                        break;
                    }
                }
                if(flag)
                    break;
            }

            //方案正确的情况下，检查step是否最小
            if(!flag) {
                if(step<minStep) {
                    list.clear();
                    minStep = step;
                    for(String x : temp) {
                        list.add(x);
                    }                   
                }
            }
            //临时集合清空
            temp.clear();
            //第i轮循环结束，恢复g状态
            for(int i=0;i<4;i++) {
                g[i]=Arrays.copyOf(backup[i], 4);
            }
        }
        System.out.println(minStep);
        for(String x:list) {
            System.out.println(x);
        }
    }

    static int[] x = {-3,-2,-1,1,2,3,0,0,0,0,0,0,0}; 
    static int[] y = {0,0,0,0,0,0,-3,-2,-1,1,2,3,0}; 
    public static void turn(int a,int b) {
        for(int i=0;i<x.length;i++) {
            int p = a+x[i];
            int q = b+y[i];
            if(p<0 || p>=4 || q<0 || q>= 4) {
                continue;
            }
            if(g[p][q]=='+') g[p][q]='-';
            else g[p][q]='+';
        }
    }
}