ABCgfed @ 2023-07-03 17:37:21
60pts
#include<bits/stdc++.h>
using namespace std;
const int N=5e6+8;
int n,a[N],q[N],k;
void merge_sort(int q[],int l,int r){
if(l>=r) return ;
int mid=(l+r)/2;
merge_sort(q,l,mid);
merge_sort(q,mid+1,r);
int k=1,i=l,j=mid+1;
while(i<=mid&&j<=r){
if(q[i]<=q[j]) a[k++]=q[i++];
else a[k++]=q[j++];
}
while(i<=mid) a[k++]=q[i++];
while(j<=r) a[k++]=q[j++];
for(i=l,j=1;i<=r;i++,j++) q[i]=a[j];
return ;
}
int main(){
scanf("%d%d",&n,&k);
for(int i=1;i<=n;i++){
scanf("%d",&q[i]);
}
merge_sort(q,1,n);
printf("%d\n",q[k+1]);
return 0;
}
by hjqhs @ 2023-07-03 17:56:43
@ABCgfed 不行 这道题正解是nth_element或快排
by Happy_Orca @ 2023-07-03 21:29:15
@ABCgfed 不行,写分治吧