c++ - 这个“选择第 k 个最小的使用分区”我哪里错了？

Question

#include<stdio.h>
#include<conio.h>

#define P(x) printf("%d\n",x);
int A[10];

void printarray()
{    
   for (int i = 0; i < 8; i++)
       printf("%d ", A[i]);

    printf("\n");
}

void swap(int *x, int *y)
{
    int temp = *x;
    *x = *y;
    *y = temp;
}

int partition(int beg, int end)
{
   int a = beg, pivot = A[beg], b = end;

   while (a < b)
   {
      while (A[a] <=pivot) a++;
      while (A[b] > pivot) b--;
      if (a < b)
      {
          swap(&A[a], &A[b]);
          a++;
          b--;
      }
   }
   A[beg] = A[b];  // restore the pivot to its original location
   A[b] = pivot;
   return b; 
}

int Select(int start, int end, int key)
{
    if (start == end)
        return A[start];

    int p = partition(start, end);
    int k = p - start + 1; // no of elements to the left of the pivot

    if (key <= k)
        return Select(start, k, key);  // left
    else
        return Select(k+1, end, key-k);// right
  }
}

int main()
{  
    // input being read from file
    freopen("inp.txt", "r", stdin);

    for (int i = 0; i < 10; i++)
    {
        scanf("%d", &A[i]);
    }

    P(A[Select(0, 7, 6)]);
    getch();

    return 0;
}

这里我使用了快速排序的分区功能对数组进行分区。我正在根据正在生成的枢轴和正在搜索的元素对分区的任一部分进行递归调用..即第 k 个最小的元素。