qsort1.h

数据结构c++语言描述 Borland C++实现

// quick sort with second recursive call of Program 14.6
// replaced by a while loop

#ifndef QuickSort_
#define QuickSort_

#include "swap.h"

template<class T>
void quickSort(T a[], int l, int r)
{// Sort a[l:r], a[r+1] has large value.
   while (l < r) {
      // at least two elements to sort
      int i = l,      // left-to-right cursor
          j = r + 1;  // right-to-left cursor
      T pivot = a[l];
   
      // swap elements >= pivot on left side
      // with elements <= pivot on right side
      while (true) {
         do {// find >= element on left side
            i = i + 1;
            } while (a[i] < pivot);
         do {// find <= element on right side
            j = j - 1;
            } while (a[j] > pivot);
         if (i >= j) break;  // swap pair not found
         Swap(a[i], a[j]);
         }
   
      // place pivot
      a[l] = a[j];
      a[j] = pivot;
   
      quickSort(a, l, j-1); // sort left segment
      l = j + 1;            // sort right segment
      }
}


template<class T>
void QuickSort(T a[], int n)
{// Sort a[0:n-1] using quick sort.
 // Requires a[n] must have largest key.
   quickSort(a, 0, n-1);
}

#endif