利用快速排序思想找出数组中第K大的数

#include <iostream>

using namespace std;

int q_sortonce(int *array, size_t size)

{

int low = 0;

int high =size - 1;

int pivot = array[low];

while (low<high)

{

while (low < high && array[high] > pivot)

--high;

array[low] = array[high];

while (low < high && array[low] < pivot)

++low;

array[high] = array[low];

}

array[low] = pivot;

return low;

}

int q_sort(int *array, int low, int high, int k)

{

int size = high - low + 1;

if(low<high)

{

int mid = q_sortonce(array, size);

if (high-mid+1 == k)

return array[mid];

else if (high - mid + 1 < k)

{

int array1[100];

for (int i = 0; i < mid-low; i++)

{

array1[i] = array[low+i];

}

//return q_sort(array1, low, mid - 1, k);

return q_sort(array1, 0, mid-low-1, k);

}

else

{

int array2[100];

for (int i = 0; i < high-mid; i++)

{

array2[i] = array[mid+1+i];

}

//return q_sort(array2, mid + 1, high, k);

return q_sort(array2, 0, high-mid-1, k);

}

}

return 0;

}

int find_kth(int *array, size_t size, int k)

{

int low = 0;

int high = size - 1;

int m_re = q_sort(array, low, high, k);

return m_re;

}

int main()

{

int n, k;

int array[100];

while (cin>>n>>k)

{

for (int i = 0; i < n; i++)

{

cin >> array[i];

}

int result = find_kth(array, n, k);

cout << result << endl;

}

system("pause");

return 0;

}