AcWing 787. 归并排序

#include <bits/stdc++.h>
using namespace std;
const int N=1e6+10;
int q[N],tmp[N];
void merge_sort(int q[],int l,int r){
    if(l>=r) return;
    int mid=l+r >>1;
    int i=l,j=mid+1;
    merge_sort(q,i,mid);
    merge_sort(q,j,r);
    int k=0;
    while(i<=mid&&j<=r){
        if(q[i]<=q[j]) tmp[k++]=q[i++];
        else tmp[k++]=q[j++];
    }
    while(i<=mid) tmp[k++]=q[i++];
    while(j<=r) tmp[k++]=q[j++];
    for(int i=l,j=0;i<=r;i++,j++)
        q[i]=tmp[j];
}
int main(){
    int n;
    scanf("%d",&n);
    for(int i=0;i<n;i++)
        scanf("%d",&q[i]);
    merge_sort(q,0,n-1);
    for(int i=0;i<n;i++)
        printf("%d ",q[i]);
    return 0;
}