八大排序算法（六）—merge

#include "SortAll.h";
using namespace std;

void merge(int *sr, int *tr, int i, int m, int t)
{
    int j, k, l;
    for (j = m + 1, k = i; i <= m&&j <= t; ++k)
    {
        if (sr[i] < sr[j])
        {
            tr[k] = sr[i++];
        }
        else
        {
            tr[k] = sr[j++];
        }
    }
    if (i <= m)
    {
        for (l = 0; l <= m - i; l++)
        {
            tr[k + l] = sr[i + l];
        }
    }
    if (j <= t)
    {
        for (l = 0; l <= t - j; l++)
        {
            tr[k + l] = sr[j + l];
        }
    }
}

void Msort(int *sr,int *tr1,int s, int t )
{
    int m;
    int tr2[MAXSIZE];
    if (s == t)
    {
        tr1[s] = sr[s];
    }
    else
    {
        m = (t+s) / 2;
        Msort(sr, tr2, s, m);
        Msort(sr, tr2, m + 1, t);
        merge(tr2, tr1, s, m, t);
    }

}

void mergeSort(int *a, int len)
{
    Msort(a, a, 0, len-1);
}


void mergePass(int *sr, int*tr, int s, int n)
{
    int i = 0;
    int j;
    while (i <= n - 2 * s + 1)
    {
        merge(sr, tr, i, i + s - 1, i + 2 * s - 1);
        i = i + 2 * s;
    }
    if (i < n - s + 1)
    {
        merge(sr, tr, i, i + s - 1, n);
    }
    else
    {
        for (j = i; j <= n; j++)
        {
            tr[j] = sr[j];
        }
    }
}

void mergeSort1(int *a, int len) //非递归
{
    int *tr = new int[MAXSIZE];//申请动态数组，也称堆内存
    int k = 1;
    while (k < len)
    {
        mergePass(a, tr, k, len-1);
        k = 2*k;
        mergePass(tr, a, k, len-1);//怎么样都把最后的排序结果放到原数组中了
        k = 2*k;
    }
    delete[]tr;
}