归并排序

#include <iostream>
#include <algorithm>
using namespace std;

void merge_sort(int *A, int x, int y, int *T)
{
    if (y - x > 1)
    {
        int m = x + (y - x) / 2;
        int p = x, q = m, i = x;
        merge_sort(A, x, m, T);
        merge_sort(A, m, y, T);
        while (p < m || q < y)
        {
            if (q >= y || (p < m&&A[p] <= A[q]))
                T[i++] = A[p++];
            else
                T[i++] = A[q++];
        }
        for (i = x; i < y; i++)
            A[i] = T[i];
    }
}


int main()
{
    int arr[5] = { 4,3,2,1 };
    int T[5];
    merge_sort(arr, 0, 4, T);
    for (int i = 0; i < 4; i++)
        cout << arr[i] << " ";
    system("pause");
}