在快排中,这样的数组元素被称为枢轴——其前面的元素全都小于它(或大于),其后面的元素全都大于它(或小于)。如此,我们很容易想到,对于一个数组,如果其全部元素都可以被称为枢轴,那么,该数组就是一个已经排序好的数组。
参考代码:
#include <stdlib.h> #include <stdio.h> #include <string.h> static int partition(void* arr, int(*cmp)(void*, void*), int left, int right, int size) { char* tmp = (char*)malloc(size); memcpy(tmp, (char*)arr + left * size, size); while (left < right) { while (left < right && cmp((char*)arr + right * size, (char*)tmp) >= 0)--right; memcpy((char*)arr + left * size, (char*)arr + right * size, size); while (left < right && cmp((char*)arr + left * size, (char*)tmp) <= 0)++left; memcpy((char*)arr + right * size, (char*)arr + left * size, size); } memcpy((char*)arr + right * size, (char*)tmp, size); return right; } static void q_sort(void* arr, int(*cmp)(void*, void*), int left, int right, int size) { if (right <= left) return; int part = partition(arr, cmp, left, right, size); q_sort(arr, cmp, left, part - 1, size); q_sort(arr, cmp, part + 1, right, size); } void quicksort(void* arr, int n, int(*cmp)(void*, void*), int size) { q_sort(arr, cmp, 0, n - 1, size); }