歸併排序極簡

  極簡，算法模板如下: 

#include<iostream>
using namespace std;
const int N = 1e6 + 10;

int n;
int q[N];
int tmp[N];

void merge_sort(int q[N], 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()
{
	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;
}