基础算法 787.归并排序

代码模板

#include<iostream>
using namespace std;
const int N = 1e6 + 10;
int n;
int q[N],tmp[N];

void mergesort(int q[],int l,int r){
    if(l>=r)return ;
    int mid = (l+r )>> 1;
    mergesort(q,l,mid);
    mergesort(q,mid+1,r);
    int k=0,i=l,j=mid+1;
    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(){
    scanf("%d",&n);
    for(int i=0;i<n;i++)scanf("%d",&q[i]);
    mergesort(q,0,n-1);
    for(int i=0;i<n;i++)printf("%d ",q[i]);
    return 0;
}