归并模版

#include <iostream>
using namespace std;
const int N=100010;
int a[N],tmp[N];
void mSort(int q[],int l,int r)
{
    if(l>=r) return ;
    int mid=l+r>>1;
    mSort(q,l,mid),mSort(q,mid+1,r);
    int i=l,j=mid+1,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(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>>a[i];
    mSort(a,0,n-1);
    for(int i=0;i<n;i++) cout<<a[i]<<" ";
    return 0;
}