347. Top K Frequent Elements（LeetCode）

Given a non-empty array of integers, return the k most frequent elements.

For example,
Given [1,1,1,2,2,3] and k = 2, return [1,2].

Note:

You may assume k is always valid, 1 ? k ? number of unique elements.
Your algorithm's time complexity must be better than O(n log n), where n is the array's size.

 1 class Solution {
 2 public:
 3     vector<int> topKFrequent(vector<int>& nums, int k) {
 4      map<int, int> m;
 5         map<int, int>::iterator ite;
 6         for (int i = 0; i < nums.size(); i++)
 7         {
 8             m[nums[i]]++;
 9         }
10         vector<int> vet;
11         int max = INT_MIN;
12         int max1 = 0;
13         while (k)
14         {
15             int count = 0;
16             for (ite = m.begin(); ite != m.end(); ite++)
17             {
18                 if (ite->second > max)
19                 {
20                     max = ite->second;
21                     max1 = ite->first;
22                     count++;
23                 }
24             }
25             m[max1] = INT_MIN;
26             if (count != 0)
27             {
28                 vet.push_back(max1);
29             }
30             max = INT_MIN;
31             k--;
32         }
33         return vet;
34     }
35 };