Leetcode 698. 划分为k个相等的子集

class Solution {
    public boolean canPartitionKSubsets(int[] nums, int k) {
        int sum = 0;
        int len = nums.length;
        for (int i = 0; i < len; i++) 
            sum += nums[i];
        
        if(sum % k != 0 ) return false;
        int avg = sum / k;
        boolean[] flag = new boolean[len];
        return help(nums,flag,avg,k,avg,0);
    }
    
    public static boolean help(int[] nums, boolean[] flag, int avg, int k, int temp, int index ){
 
        if (k == 0 ) return true;
 
        if (temp == 0)
            return help(nums,flag,avg,k-1,avg,0);
 
        for (int i = index; i < nums.length; i++) {
            if (flag[i] == true) continue;
 
            flag[i] = true;
            if(temp-nums[i]>=0 && help(nums,flag,avg,k,temp-nums[i],index+1)){
                return true;
            }
            flag[i] = false;
 
        }
 
        return false;
    }
}