29、剑指offer--最小的K个数

 1 class Solution {
 2 public:
 3     vector<int> GetLeastNumbers_Solution(vector<int> input, int k) {
 4         vector<int> result;
 5         if(input.empty() || k<1 || input.size()<k)
 6             return result;
 7         multiset<int> insert_set;
 8  
 9         set<int>::iterator it; //定义前向迭代器
10         multiset<int>::reverse_iterator rit; //定义反向迭代器
11         for(int i=0;i<input.size();i++)
12         {
13  
14             if(i<k)
15             {
16                 insert_set.insert(input[i]);
17             }
18  
19             else
20             {
21                 rit = insert_set.rbegin();
22                 if(input[i] < *rit)
23                 {
24  
25                     insert_set.erase(*rit);
26                     insert_set.insert(input[i]);
27                 }
28             }
29         }
30  
31  
32         for(it = insert_set.begin(); it != insert_set.end(); it++)
33         {
34             result.push_back(*it);
35         }
36         return result;
37     }
38 };