排序算法-归并排序

#include "iostream"
#include "algorithm"

using namespace std;

const int N = 1e6+10;
int q[N];
int tmp[N];

void mergeSort(int l,int r){

    if(l >= r) return;

    int mid = (l + r) / 2;

    mergeSort(l,mid);
    mergeSort(mid+1,r);

    int i = l,j = mid + 1;
    int cnt = 0;

    while(i <= mid && j <= r){
        if(q[i] < q[j]){
            tmp[cnt++] = q[i++];
        }else{
            tmp[cnt++] = q[j++];
        }
    }

    while(i <= mid){
        tmp[cnt++] = q[i++];
    }

    while(j <= r){
        tmp[cnt++] = q[j++];
    }

    for(int i = l,j = 0; i <= r; i++,j++){
        q[i] = tmp[j];
    }

}
int main(){

    int n;cin >> n;

    for(int i = 0; i < n; i++){
        cin >> q[i];
    }

    mergeSort(0,n-1);

    for(int i = 0; i < n; i++){
        cout << q[i] << ' ';
    }

    return 0;
}