编程算法 - 排序分割 代码(C)

排序分割 代码(C)

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排序分割, 把一个数组分为, 大于k\小于k\等于k的三个部分.

可以使用快速排序的Partition函数, 进行处理, 把大于k的放在左边, 小于k的放在右边.

使用一个变量记录中间的位置, 则时间复杂度为O(3n/2).

代码:

/* * main.cpp * *  Created on: 2014.9.18 *      Author: Spike *//*eclipse cdt, gcc 4.8.1*/#include <iostream>#include <list>#include <queue>#include <string.h>#include <stdlib.h>using namespace std;int RandomInRange(int min, int max) {return rand()%(max-min+1) + min;}void Swap(int* num1, int* num2) {int tmp = *num1;*num1 = *num2;*num2 = tmp;}int PartitionK (int data[], int length, int k){if (data == NULL || length <= 0)return -1;int small = -1;int index = 0;for (index=0; index<length; ++index) {if (data[index] < k) {small++;if (small != index)Swap(&data[small], &data[index]);}}int pos = ++small; //记录位置small = length;index = 0;for (index = length-1; index>=pos; index--) {if (data[index] > k) {small--;if (small != index)Swap(&data[small], &data[index]);}}return --small;}int main (void){int data[] = {1, 3, 2, 5, 2, 0, 5, 2, -1, 0, 4};int length = sizeof(data)/sizeof(data[0]);PartitionK(data, length, 2);for (int i=0; i<length; ++i) {cout << data[i] << " ";}cout << endl;return 0;}

输出:

1 0 -1 0 2 2 2 3 5 5 4