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return不可能返回数组,于是子hanshu1quicksort最后没有用return,但是没有return又怎么可以更改a[N]?主函数中的quicksort(a, 0, N - 1);将a[N]复制后传递给形参a,quicksort(a, 0, N - 1);应该是只对a[N]的副本进行排序,最后输出的顺序应该和输入的一样,相当于没有排,但是结果却是排了,这是怎样实现的?和理论不是矛盾吗?
/*********************************************************
* From C PROGRAMMING: A MODERN APPROACH, Second Edition *
* By K. N. King *
* Copyright (c) 2008, 1996 W. W. Norton & Company, Inc. *
* All rights reserved. *
* This program may be freely distributed for class use, *
* provided that this copyright notice is retained. *
*********************************************************/
/* qsort.c (Chapter 9, page 207) */
/* Sorts an array of integers using Quicksort algorithm */
#include
#define N 10
void quicksort(int a[], int low, int high);
int split(int a[], int low, int high);
int main(void)
{
int a[N], i;
printf("Enter %d numbers to be sorted: ", N);
for (i = 0; i < N; i++)
scanf("%d", &a[i]);
quicksort(a, 0, N - 1);
printf("In sorted order: ");
for (i = 0; i < N; i++)
printf("%d ", a[i]);
printf("\n");
return 0;
}
void quicksort(int a[], int low, int high)
{
int middle;
if (low >= high) return;
middle = split(a, low, high);
quicksort(a, low, middle - 1);
quicksort(a, middle + 1, high);
}
int split(int a[], int low, int high)
{
int part_element = a[low];
for (;;) {
while (low < high && part_element <= a[high])
high--;
if (low >= high) break;
a[low++] = a[high];
while (low < high && a[low] <= part_element)
low++;
if (low >= high) break;
a[high--] = a[low];
}
a[high] = part_element;
return high;
}