合并排序

复杂度

最坏时间复杂度

 

最好时间复杂度

 

空间复杂度

 

#include<iostream>
#include<vector>
using namespace std;
void merge1(int a[], int p, int m, int q)
{
    int c = m - p + 1;
    int b = q - m;
    //int L[c + 1], R[b + 1];
    //int *L = new int[c + 1];
    //int *R = new int[b + 1];
    vector<int> L(c + 1);
    vector<int> R(b + 1);
    for (int i = 0; i < c; i++)
    {
        L[i] = a[p + i];
    }
    for (int i = 0; i < b; i++)
    {
        R[i] = a[m + i + 1];
    }
    L[c] = INT_MAX;
    R[b] = INT_MAX;
    int i ,j;
    i = j = 0;
    for (int k = p; k <= q; k++)
    {
        if (L[i] < R[j])
        {
            a[k] = L[i];
            i++;
        }
        else
        if (L[i] >= R[j])
        {
            a[k] = R[j];
            j++;
        }
    }
}
void recursive_mergesort(int a[], int p, int q)
{
    if (p < q)
    {
        int m = (q + p) / 2;
        recursive_mergesort(a, p, m);
        recursive_mergesort(a, m + 1, q);
        merge1(a, p, m, q);
    }
}
int main()
{
    int a[] = { 1, 5, 6, 88, 8, 99, 88, 0, 1 };
    for (auto s : a)
        cout << s << " ";
    cout << endl;
    recursive_mergesort(a, 0, 8);
    for (auto s : a)
        cout << s << " ";
    system("pause");
    return 0;
}