快排思想求给定序列中第k大的数

#include <iostream>
#include <vector>

int QuockSort(int* array, int size, int k,std::vector<int>& vtmparr)
{
int first = 0;
int last = size - 1;
int key = 0;
int i = 0;
for (; i < vtmparr.size(); ++i){
if (key == vtmparr[i]){
++key;
i = 0;
}
}
first = key;
int tmp = array[key];
while (first <= last){
while (first <= last && array[last] >= tmp){
--last;
}
if (first <= last){
std::swap(array[key], array[last]);
key = last;
}
while (first <= last && array[first] <= tmp){
++first;
}
if (first <= last){
std::swap(array[key], array[first]);
key = first;
}
}
return key;
}

int NumOfKMax(int* array,int size,int k,std::vector<int>& vtmparr)
{
static int i = 0;
int ret = -1;
while (ret != size - k){
ret = QuockSort(array, size, k,vtmparr);//ret为下标为ret的数据到达正确的位置
vtmparr.push_back(ret);
}
return array[ret];
}

int main()
{
int array[7] = {4,8,2,3,6,7,0};
std::vector<int> vtmparr;
int k = 7;
int num = NumOfKMax(array,sizeof(array)/sizeof(array[0]), k,vtmparr);
std::cout << num << std::endl;

system("pause");
return 0;
}