开启O2最后两个点WA了，求助dalaoQAQ

Lilin_ @ 2023-08-19 11:22:45

#include<bits/stdc++.h>
using namespace std;
long long a[2500000],b[2500001];
int main(){
    int n=0,k=0;
    cin>>n>>k;
    if(n>2500000){
        for(int i=0;i<2500000;i++){
            scanf("%lld",&a[i]);
        }
        sort(a,a+2500000);
        for(int i=0;i<n-2500000;i++){
            scanf("%lld",&b[i]);
        }
        sort(b,b+(n-2500000));
        if(k>2500000) cout<<b[k-2500000];
        else cout<<a[k];
    }
    else{
        for(int i=0;i<n;i++){
            scanf("%lld",&a[i]);
        }
        sort(a,a+n);
        cout<<a[k];
    }
}

by siuuuuu @ 2023-08-19 11:41:56

#include<iostream>
#include<algorithm>
const int maxn=1e6*5+10;
using namespace std;
int k,n,a[maxn];
void qsort(int s,int e){
    int mid=(s+e)/2,flag=a[mid],l=s,r=e;
    do{
        while(a[l]<flag)l++;
        while(a[r]>flag)r--;
        if(l<=r){
            swap(a[l],a[r]);
            l++;
            r--;
        } 
    }while(l<=r);
    if(k<=r){
        if(s<r)qsort(s,r);
        else return;
    }else if(k>=l){
        if(l<e)qsort(l,e);
        else return;
    }
    return;
}
int main(){
    ios::sync_with_stdio(false);
    cin>>n>>k;
    for(int i=0;i<n;i++)
        cin>>a[i];
    qsort(0,n-1);
    cout<<a[k];
    return 0;
}

我不应该帮诈骗犯的

by Lilin_ @ 2023-08-20 20:00:47

@niganmaaiyou 没看到，不好意思，谢谢dalaoQAQ

Never gonna give you up