473. Matchsticks to Square

Posted 2022-08-21 cznczai

https://www.acwing.com/solution/LeetCode/content/3785/

class Solution 
    private boolean flag;

    public boolean makesquare(int[] nums) 
        int temp = 0;
        for (int i = 0; i < nums.length; i++) 
            temp += nums[i];
        
        if (nums.length == 0 || temp % 4 != 0)
            return false;
        int count[] = new int[4];
        Arrays.sort(nums);
        dfs(nums, count, nums.length-1,temp/4);
        return flag;
    

    private void dfs(int[] nums, int[] count, int x,int avg) 
        if (x == -1) 
            for (int i = 0; i < 3; i++) 
                if (count[i] != count[i + 1])
                    return;
            
            flag = true;
         else 
            count[0] += nums[x];
            if(count[0]<=avg)dfs(nums, count, x - 1,avg);
            count[0] -= nums[x];
            count[1] += nums[x];
            if(count[1]<=avg)dfs(nums, count, x - 1,avg);
            count[1] -= nums[x];
            count[2] += nums[x];
            if(count[2]<=avg)dfs(nums, count, x - 1,avg);
            count[2] -= nums[x];
            count[3] += nums[x];
            if(count[3]<=avg)dfs(nums, count, x - 1,avg);
            count[3] -= nums[x];