[LUOGU] P3611 [USACO17JAN]Cow Dance Show奶牛舞蹈

https://www.luogu.org/problemnew/show/P3611

二分答案+优先队列

二分O(logn) 判一次正确性O(nlogn) 总体O(nlognlogn)

为了让priority_queue变成小根堆，就把元素全部取相反数了。

#include<iostream>
#include<cstdio>
#include<queue>

using namespace std;

inline int rd(){
  int ret=,f=;char c;
  while(c=getchar(),!isdigit(c))f=c=='-'?-:;
  while(isdigit(c))ret=ret*+c-'',c=getchar();
  return ret*f;
}

const int MAXN=;

int n,t;
int d[MAXN];
priority_queue<int> Q;

bool check(int x){
  for(int i=;i<=x;i++) Q.push(d[i]);
  for(int i=x+;i<=n;i++){
    int top=Q.top();Q.pop();
    Q.push(top+d[i]);
  }
  int ret=;
  while(!Q.empty()){ret=max(ret,-Q.top());Q.pop();}
  return ret<=t;
}

int main(){
  n=rd();t=rd();
  for(int i=;i<=n;i++) d[i]=-rd();
  int l=,r=n;
  int ans;
  while(l<=r){
    int mid=(l+r)>>;
    if(check(mid))r=mid-,ans=mid;
    else l=mid+;
  }
  printf("%d\n",ans);
  return ;
}