归并排序模板

• 归并排序

#include<iostream>
using namespace std;
const int N =1e6+10;
int n;
int q[N];
int tmp[N];
void merge_sort(int q[],int le ,int r)
{
if(le>=r)return;
int mid=(le+r)>>1;
merge_sort(q,le,mid);
merge_sort(q,mid+1,r);
int k=0,i=le,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=le,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]);
merge_sort(q,0,n-1);
for(int i=0;i<n;i++)printf("%d  ",q[i]);
return 0;
}