The minimum number k Leetcode

Title Description

Input integer array arr, find the smallest number k. For example, digital input 4,5,1,6,2,7,3,8 eight, the minimum number is four 1,2,3,4.

Thinking

1. Hash table, the title given arr.length <10000, arr [i] <10000, the number of times to establish a record for each array Hash number appears, then [0] is output from the Hash, if the Hash [i]> 0 , the output of the cycle until the Hash [i] = 0 or k = 0
2. Heap ideas

Code

class Solution {
public:
    vector<int> getLeastNumbers(vector<int>& arr, int k) {
        vector<int> res;
        if(arr.size()==0 || k==0)
            return res;
        vector<int> Hash(10000);
        for(int i = 0;i<arr.size();i++)
        {
            Hash[arr[i]]++;
        }
        int count = 0;
        while(k>0)
        {
            while(Hash[count]>0 && k > 0)
            {
                res.push_back(count);
                Hash[count]--;
                k--;
            }
            count++;
        }
        return res;
    }
};

Method Two:

class Solution {
public:
    vector<int> getLeastNumbers(vector<int>& arr, int k) {
        vector<int> res;
        if(k == 0){
            return res;
        }
        priority_queue<int> h;
        for(int num : arr){
            if(h.size() < k){
                h.push(num);
            }else{
                if(h.top() <= num){
                    continue;
                }else{
                    h.pop();
                    h.push(num);
                }
            }
        }
        while(!h.empty()){
            res.push_back(h.top());
            h.pop();
        }
        return res;
    }
};