class Solution {

 public:

     vector<int> GetLeastNumbers_Solution(vector<int> input, int k) {

         int iSize = input.size();

         if(k == iSize) return input;

         vector<int> leastNumbers;

         if(k <=  || k > iSize) return leastNumbers;

         leastNumbers.push_back();  // 使下标为0的位置为0，不使用该位置，便于访问后面的元素

         for(int i = ; i < k; i++) {    // 初始化一个k大小的堆

             leastNumbers.push_back(input[i]);

         }

         for(int i = k / ; i > ; --i) {

             HeapAdjust(leastNumbers, i, k); // 调整为大根堆

         }

         for(int i = k; i < iSize; i++) {

             if(input[i] < leastNumbers[]) {

                 leastNumbers[] = input[i];

                 HeapAdjust(leastNumbers, , k);  // 调整为大根堆

             }

         }

         leastNumbers.erase(leastNumbers.begin());   // 移除第0位置的0

         return leastNumbers;

     }

     void HeapAdjust(vector<int> &input, int s, int m) { // 调整堆

         int rc = input[s];

         for(int j = (s << ); j <= m; j <<= ) {

             if(j < m && input[j] < input[j + ]) ++j;

             if(rc > input[j]) break;

             input[s] = input[j];

             s = j;

         }

         input[s] = rc;

     }

 };