Leetcode: Matchsticks to Square

Remember the story of Little Match Girl? By now, you know exactly what matchsticks the little match girl has, 
please find out a way you can make one square by using up all those matchsticks. You should not break any stick, 
but you can link them up, and each matchstick must be used exactly one time.

Your input will be several matchsticks the girl has, represented with their stick length. Your output will either be true or false, 
to represent whether you could make one square using all the matchsticks the little match girl has.

Example 1:
Input: [1,1,2,2,2]
Output: true

Explanation: You can form a square with length 2, one side of the square came two sticks with length 1.
Example 2:
Input: [3,3,3,3,4]
Output: false

Explanation: You cannot find a way to form a square with all the matchsticks.
Note:
The length sum of the given matchsticks is in the range of 0 to 10^9.
The length of the given matchstick array will not exceed 15.

Better Solution: DFS, but only scan all the matches once! If a match can not make the 1st edge, then we do not discard it, we try 2nd, 3rd, 4th edge

public boolean makesquare(int[] nums) {
    if (nums.length < 4) return false;
        
    int perimeter = 0;
    for (int ele : nums) perimeter += ele;
    if (perimeter % 4 != 0) return false;
        
    Arrays.sort(nums);
    int side = perimeter / 4;

    return makesquareSub(nums, nums.length - 1, new int[] {side, side, side, side});
}
    
private boolean makesquareSub(int[] nums, int i, int[] s) {
    if (i < 0) return s[0] == 0 && s[1] == 0 && s[2] == 0 && s[3] == 0;
        
    for (int j = 0; j < s.length; j++) {
        if (nums[i] > s[j]) continue;
        s[j] -= nums[i];
        if (makesquareSub(nums, i - 1, s)) return true;
        s[j] += nums[i];
    }
        
    return false;
}