Acwing787.归并排序
归并模板
归并排序,合二为一
题目链接:Acwing787.归并排序
#include<iostream>
using namespace std;
const int N =1e6+10;
int n ;
int q[N],temp[N];
void merge_sort(int q[],int l ,int r )
{
if(l >=r)return ;
int mid =l+r >>1;
merge_sort(q,l,mid),merge_sort(q,mid+1,r);
int k = 0 , i = l , j = mid +1 ;
while( i <= mid && j <= r)
if(q[i]<=q[j])temp[k++]=q[i++];
else temp[k++]=q[j++];
while(i<=mid)temp[k++]=q[i++];
while(j<=r)temp[k++]=q[j++];
for(i = l ,j=0;i<=r ;i++,j++)q[i]=temp[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]);
}
练习题:Acwing788.逆序对的数量
欠着。晚点补。