归并排序

注没有排序那一步，在分解的时候你就把它分解成一个个的，相当于排好了序的，所以直接归并就行了

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

void merge(int *a, int p, int q, int r) {
    int n1 = q - p + 1;
    int n2 = r - q;
    int *L = new int[n1];
    int *R = new int[n2];
    for (int i = 0; i < n1; i++)
        L[i] = a[p + i];
    for (int i = 0; i < n2; i++)
        R[i] = a[q + 1 + i];
    int key = p;
    int i = 0, j = 0;
    while (i < n1 || j < n2) {
        if (i < n1&&j < n2)
            if (L[i] < R[j]) a[key++] = L[i++];
            else a[key++] = R[j++];
        else
            if (i < n1) a[key++] = L[i++];
            else a[key++] = R[j++];
    }
        delete[] L;
        delete[] R;
        return;
    }

void mergeSort(int *a, int l, int r) {
    if (l < r) {
        int m = (l + r) / 2;
        mergeSort(a, l, m);
        mergeSort(a, m + 1, r);
        merge(a, l, m, r);
    }
    return;
}


int main() {
    int a[100];
    int n;
    while (cin>>n)
    {
        for (int i = 0; i < n; i++)
            cin >> a[i];

        mergeSort(a, 0, n - 1);

        for (int i = 0; i < n; i++)
            cout << a[i] << " ";
        cout << endl;
    }
}