分治法——3.4快速排序

#include<iostream>
using namespace std;
int Partition(int r[], int low, int high)
{
  int i = low, j = high, pivot = r[low];
  while (i<j)
  {
    while (i<j&&r[j]>pivot)
      j--;
    if (i < j)
      swap(r[i++], r[j]);
    while (i < j&&r[i] <= pivot)
      i++;
    if (i < j)
      swap(r[i], r[j--]);
  }
  return i;//返回基准元素的位置
}

void QuickSort(int R[], int low, int high)
{
  int mid;
  if (low < high)
  {
    mid = Partition(R, low, high);
    QuickSort(R, low, mid -1);
    QuickSort(R, mid, high);
  }
}