P7557 [USACO21OPEN] Acowdemia S

典型二分：

#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N=1e5+10;
int n,a[N],k,l;
bool check(int x) {int cnt=0,ans=0;for(int i=1; i<=x; i++) {if(a[i]>=x) {cnt++;continue;}else{if(x-a[i]>k)return false;else{ans=ans+x-a[i];	}}}return ans<=k*l;
}
bool cmp(int i,int j) {return i>j;
}
void solve() {cin>>n>>k>>l;for(int i=1; i<=n; i++) cin>>a[i];sort(a+1,a+1+n,cmp);int l=-1,r=n+1;while(l+1<r) {int mid=l+r>>1;if(check(mid))l=mid;else r=mid;}cout<<l<<"\n";
}
signed main() {ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);int t=1;//cin>>t;while(t--) {solve();}return 0;
}#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N=1e5+10;
int n,a[N],k,l;
bool check(int x) {int cnt=0,ans=0;for(int i=1; i<=x; i++) {if(a[i]>=x) {cnt++;continue;}else{if(x-a[i]>k)return false;else{ans=ans+x-a[i];	}}}return ans<=k*l;
}
bool cmp(int i,int j) {return i>j;
}
void solve() {cin>>n>>k>>l;for(int i=1; i<=n; i++) cin>>a[i];sort(a+1,a+1+n,cmp);int l=-1,r=n+1;while(l+1<r) {int mid=l+r>>1;if(check(mid))l=mid;else r=mid;}cout<<l<<"\n";
}
signed main() {ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);int t=1;//cin>>t;while(t--) {solve();}return 0;
}

over~