基础算法（二）归并排序模板

模板如下

#include<iostream>
using namespace std;

const int N=1000010;
int q[N],tmp[N];

void merge_sort(int q[],int l,int r){
    if(l>=r)return;
    int mid = (l+r)>>1;
     int k=0,i=l,j=mid+1;
   
    merge_sort(q,l,mid);
    merge_sort(q,mid+1,r);

    
    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 j=0;j<n;j++)cout<<q[j]<<" ";
    return 0;
}