思路

sort，然后从中点向后维护。

代码

#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N = 2e5+10;

int a[N], n, k;


signed main(){
    cin>>n>>k;
    for(int i = 1; i <= n; i++) cin>>a[i];
    sort(a+1, a+1+n);
    int mid = n / 2+1;
    int tmp = 0;
    int len;
    for(int i = mid; i < n; i++){
        len = i - mid + 1;
        int w = a[i+1]-a[i];

        if(k/len <= w){
            cout<<a[i]+k/len<<endl;
            goto done;
        }
        k -= w*len;
    }
    len = n - mid + 1;
    cout<<a[n]+(k/len)<<endl;


done:;

    return 0;
}