c++: class Solution { public:

int avg;
bool canPartitionKSubsets(vector<int>& nums, int k) {
    int sum = 0;
    for(auto p:nums){
        sum+=p;
    }
    if(sum % k !=0) return false;
    avg =  sum / k;
    vector<bool> vis(nums.size(),false);
    return dfs(nums.size()-1,avg,nums,nums.size(),vis); 
}
bool dfs(int start,int target,vector<int> &nums,int remains,vector<bool> &vis){
    if(remains==0)return true;
    bool flag = false;
    for(int i = start;i >= 0;--i){
        if(!vis[i]&&target>=nums[i]){
            vis[i]=true;
            if(target == nums[i])flag = dfs(nums.size()-1,avg,nums,remains-1,vis);
            else flag = dfs(i-1,target-nums[i],nums,remains-1,vis);
            if(flag)return flag;
            vis[i]=false;
           // while(i>=1&&nums[i]==nums[i-1])i--;
        }
    }
    return flag;
}

};