自然归并排序

#include<iostream>

using namespace std;

int Search(int *a, int *b, int n);
void Merge(int *a, int left, int mid, int right);
void MergeSort(int *a, int *b, int num,int n);
void MergePass(int *a, int *b, int s, int num, int n);
void output(int *a, int n);

int main()
{
    int n,num;
    int *a;
    int *b;
    cin >> n;
    a = (int *)malloc(n * sizeof(int));
    b = (int *)malloc(n * sizeof(int));
    for (int i = 0; i < n;i++)
    {
        cin >> a[i];
    }
    num= Search(a,b,n);
    MergeSort(a, b,num,n);
    output(a, n);
    return 0;
}

int Search(int *a,int *b,int n)
{
    int j = 0;
    b[j++] = 0;
    for (int i = 0; i < n - 1;i++)
    {
        if(a[i+1]<a[i])
        {
            b[j++] = i + 1;
        }
    }
    b[j++] = n;
    return j;
}

void MergeSort(int *a,int *b,int num,int n)
{
    int s = 1;
    while(s<(num-1))
    {
        MergePass(a, b,s,num,n);
        s <<= 1;
    }
}

void MergePass(int *a,int *b,int s,int num,int n)
{
    int i = 0;
    while(i<=num-1-2*s)
    {
        Merge(a, b[i], b[i + s] - 1, b[i + 2 * s] - 1);
        i = i + 2 * s;
    }

    if(i+s<num-1)
    {
        Merge(a, b[i], b[i + s] - 1, b[i+2*s]-1);
    }
}

void Merge(int *a,int left,int mid,int right)
{
    int i = left;
    int j = mid+1;
    int k = 0;
    int *tmp = (int *)malloc((right - left + 1) * sizeof(int));
    while(i<=mid&&j<=right)
    {
        if(a[i]<=a[j])
        {
            tmp[k++] = a[i++];
        }
        
        else
        {
            tmp[k++] = a[j++];
        }
    }

    while(i<=mid)
    {
        tmp[k++] = a[i++];
    }

    while(j<=right)
    {
        tmp[k++] = a[j++];
    }

    for (i = left, k = 0; i <= right;i++,k++)
    {
        a[i] = tmp[k];
    }
}

void output(int *a,int n)
{
    for (int i = 0; i < n;i++)
    {
        cout << a[i] << endl;
    }
}

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转载自blog.csdn.net/yy1348046572/article/details/85919944