快排实现-优快云博客

本文链接：https://blog.youkuaiyun.com/Edwards_June/article/details/54380556

本文介绍了一个使用C语言实现的快速排序算法。通过递归方式，该程序能够接收用户输入的整数数组并进行排序，同时提供了打印排序前后数组的功能。核心部分包括分区函数和交换元素的函数。

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#include <stdio.h>
#include <stdlib.h>

void swap(int arr[], int i, int j) {
	int temp = arr[i];
	arr[i] = arr[j];
	arr[j] = temp;
}

int partition(int arr[], int low, int high) {
	int temp = arr[low];
	int left = low;
	int right = high;
	while (left != right) {
		while (temp <= arr[right] && left < right) {
			right--;
		}
		while (temp >= arr[left] && left < right) {
			left++;
		}
		if (left < right) {
			swap(arr, left, right);
		}
	}
	return left;
}
void quicksort(int arr[], int low, int high) {
	if (low >= high) {
		return;
	}
	int temp = arr[low];

	int pivot = partition(arr, low, high);

	arr[low] = arr[pivot];
	arr[pivot] = temp;

	quicksort(arr, low, pivot - 1);
	quicksort(arr, pivot + 1, high);
}

void printIntArray(int array[], int length) {
	int i;
	for (i = 0; i < length; i++) {
		printf("%3d", array[i]);
	}
}

int main(void) {
	setvbuf(stdout, NULL, _IONBF, 0);
	int len = 0;
	int i = 0;
	printf("input length: ");
	scanf("%d", &len);
	printf("input array elements: ");
	int arr[len];
	for (; i < len; i++) {
		scanf("%d", &arr[i]);
	}
	printf("Before sorted:\n");
	printIntArray(arr, len);
	quicksort(arr, 0, len - 1);
	printf("\nAfter sorted:\n");
	printIntArray(arr, len);

	return EXIT_SUCCESS;
}