第三周作业——冒泡排序和归并排序

#include <iostream>
#include "stdafx.h"
#include <fstream>
#include <string.h>
#include <time.h>
#include <Windows.h>

using namespace std;
#define NUM_AMOUNT 10000000		//已知为1000000个数据

/*template <class T>
int getArrayLen(T& array)
{
	return (sizeof(array) / sizeof(array[0]));
}
*/
int getDataFromFile(const char *filename,int *data)			//将txt文档的数字存入data数组
{
	ifstream LargeData;
	int index = 0;
	LargeData.open(filename, ios::in);
	if (!LargeData)
	{
		cerr << "the fucking file openning failed!" << endl;
		exit(1);
	}

	while(!LargeData.eof())						
	{
		LargeData >> data[index++];
	}
	LargeData.close();
	return index;
}

void writeToFile(const char * fileneme, int * data, int index)			//将排序好的数组数据写入新的txt文档
{
	fstream datafile;
	datafile.open(fileneme, ios::out|ios::trunc);
	if (!datafile)
	{
		cerr << "file open failed!" << endl;
		exit(1);
	}
	for (int i = 0; i < index; i ++)
	{
		datafile << data[i] << endl;
	}
	datafile.close();
}

void bubbleSort(int * array,int index)			//冒泡排序法  
{  
    int tem;  
    for(int i = 0;i < index - 1;i ++)  
    {  
        for(int j = 0;j < (index-i-1);j ++)  
            if(array[j] > array[j+1])  
            {  
                tem = array[j];  
                array[j] = array[j+1];  
                array[j + 1] = tem;  
            }  
        cout << array[i] << endl;  
    }  
}  

void merge_array(int *list1, int list1_size, int *list2, int list2_size)			//归并排序算法参考wiki
{
	int i, j, k;
	i = j = k = 0;

	// 声明临时数组用于存储归并结果
	//int list[list1_size + list2_size];
	int * list = new int[list1_size + list2_size];
	// note: 只要有一个数组到达了尾部就要跳出
	// 也就是说只有两个都没有到达尾部的时候才执行这个循环
	while (i < list1_size && j < list2_size)
	{
		// 把较小的那个数据放到结果数组里， 同时移动指针
		list[k++] = list1[i] < list2[j] ? list1[i++] : list2[j++];
	}

	// 如果 list1 还有元素，把剩下的数据直接放到结果数组
	while (i < list1_size)
	{
		list[k++] = list1[i++];
	}

	// 如果 list2 还有元素，把剩下的数据直接放到结果数组
	while (j < list2_size)
	{
		list[k++] = list2[j++];
	}

	// 把结果数组 copy 到 list1 里
	for (int ii = 0; ii < (list1_size + list2_size); ++ii)
	{
		list1[ii] = list[ii];
	}

}

void merge_sort(int *list, int list_size)
{
	if (list_size > 1)
	{
		// 把数组平均分成两个部分
		int *list1 = list;
		int list1_size = list_size / 2;
		int *list2 = list + list_size / 2;
		int list2_size = list_size - list1_size;
		// 分别归并排序
		merge_sort(list1, list1_size);
		merge_sort(list2, list2_size);

		// 归并
		merge_array(list1, list1_size, list2, list2_size);
	}
}

int main()
{
	time_t begin, end;
	double cost;
	int tem_index;
	int * data = new int[NUM_AMOUNT];
	tem_index = getDataFromFile("LargeW.txt", data);

	time(&begin);
	//bubbleSort(data,tem_index - 1);
	merge_sort(data,tem_index - 1);
	//Sleep(1000);
	time(&end);
	cost = difftime(end,begin);

	cout << data[NUM_AMOUNT - 1] << endl;
	//cout << "Bubble Sorting cost " << cost << "s" << endl;
	cout << "Merge Sorting cost " << cost << "s" << endl;

	//writeToFile("largeW_bubble.txt", data, tem_index - 1);			//冒泡排序法所得的数据输出到largeW_bubble.txt
	writeToFile("largeW_merge.txt", data, tem_index - 1);			//冒泡排序法所得的数据输出到largeW_merge.txt
	delete []data;	
	
	return 0;
}

一开始因为difftime函数的参数位置弄反了导致显示时间为负数

冒泡排序：

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归并排序：