算法搬运之归并排序

原文连接：http://www.cnblogs.com/Braveliu/archive/2013/01/14/2860456.html

#include<iostream>
using namespace std;

//将有序数组ar[]和br[]合并到cr[]中
void MemeryArray(int a[], int n, int b[], int m, int c[])
{
    int i, j, k;

    i = j = k = 0;
    while (i < n && j < m)
    {
        if (a[i] < b[j])
            c[k++] = a[i++];
        else
            c[k++] = b[j++]; 
    }

    while (i < n)
        c[k++] = a[i++];

    while (j < m)
        c[k++] = b[j++];
}

void  PrintArr(int ar[],int n)
{
    for(int i = 0; i < n; ++i)
        cout<<ar[i]<<" ";
    cout<<endl;
}

void main()
{
    int ar[5] = {12, 23, 34, 45, 56};
    int br[5] = {13, 24, 35, 46, 60};
    int cr[10];
    cout<<"数组ar为："<<endl;
    PrintArr(ar, 5);
    cout<<"数组br为："<<endl;
    PrintArr(ar, 5);
    MemeryArray(ar, 5, br, 5, cr);
    cout<<"合并后结果为："<<endl;
    PrintArr(cr, 10);
}

/*
数组ar为：
12 23 34 45 56
数组br为：
12 23 34 45 56
合并后结果为：
12 13 23 24 34 35 45 46 56 60
*/

#include<iostream>
using namespace std;

#define  MAXSIZE  10

//将两个有序数列a[first...mid] 和 a[mid...last] 合并。
void mergearray(int a[], int first, int mid, int last, int temp[])
{
    int i = first, j = mid + 1;
    int m = mid, n = last;
    int k = 0;

    while (i <= m && j <= n)
    {
        if (a[i] <= a[j])
            temp[k++] = a[i++];
        else
            temp[k++] = a[j++];
    }

    while (i <= m)
        temp[k++] = a[i++];

    while (j <= n)
        temp[k++] = a[j++];

    for (i = 0; i < k; ++i)
        a[first + i] = temp[i];
}
void mergesort(int a[], int first, int last, int temp[])
{
    if (first < last)
    {
        int mid = (first + last) / 2;
        mergesort(a, first, mid, temp);     //左边有序
        mergesort(a, mid + 1, last, temp);  //右边有序
        mergearray(a, first, mid, last, temp); //再将两个有序数列合并
    }
}

bool MergeSort(int a[], int n)
{
    int *p = new int[n];
    if (p == NULL)
        return false;
    mergesort(a, 0, n - 1, p);
    delete[] p;
    return true;
}

void  PrintArr(int ar[],int n)
{
    for(int i = 0; i < n; ++i)
        cout<<ar[i]<<" ";
    cout<<endl;
}

void main()
{
    int ar[MAXSIZE] = {23, 34, 45, 78, 90, 12, 49, 92, 32, 19};
    PrintArr(ar, MAXSIZE);
    bool bValue = MergeSort(ar, MAXSIZE);
    if(!bValue)
    {
        cout<<"MergeSort  Failed!! "<<endl;
    }
    PrintArr(ar, MAXSIZE);
}

#include<iostream>
#include<malloc.h>
using namespace std;

#define   MAXSIZE  10

void  PrintArr(int ar[],int n)
{
    for(int i = 0; i < n; ++i)
        cout<<ar[i]<<" ";
    cout<<endl;
}

static void merge(int ar[], int low, int mid, int high)  
{  
    int i, k = 0;  
    //申请空间，使其大小为两个已经排序序列之和，该空间用来存放合并后的序列   
    int *temp = (int *)malloc((high - low + 1)*sizeof(int));   
    int begin1 = low;  
    int end1 = mid;

    int begin2 = mid + 1;  
    int end2 = high;   

    //比较两个元素，选择相对小的元素放入到合并空间，并移动指针到下一位置   
    for (k = 0; begin1 <= end1 && begin2 <= end2;)    
    {  
        if(ar[begin1] < ar[begin2])  
            temp[k++] = ar[begin1++];  
        else  
            temp[k++] = ar[begin2++];    
    }   

    while(begin1 <= end1)  //若第一个序列有剩余，直接拷贝出来粘到合并序列尾   
        temp[k++] = ar[begin1++];  
    while(begin2 <= end2)  //若第二个序列有剩余，直接拷贝出来粘到合并序列尾   
        temp[k++] = ar[begin2++];  

    for (i = 0;i < k; i++)   //将排序好的序列拷贝回数组中  
    {
        ar[low+i] = temp[i]; 
    }

    free(temp);  
}  
void merge_sort(int ar[],int begin,int end)  
{  
    int mid = 0;  
    if(begin < end)  
    {  
        mid = (begin + end) / 2;
        merge_sort(ar, begin, mid); 
        merge_sort(ar, mid + 1, end);
        merge(ar, begin, mid, end);  
    }  
}  

void  main()
{
    int  ar[] = {12, 14, 54, 5, 6, 3, 9, 8, 47, 89};
    merge_sort(ar, 0, MAXSIZE-1);
    PrintArr(ar, MAXSIZE);
}

/*
*3 5 6 8 9 12 14 47 54 89
 */