Submission #955128

#	Time	Username	Problem	Language	Result	Execution time	Memory
955128		edogawa_something	Sparklers (JOI17_sparklers)	C++17	0 / 100	1 ms	460 KiB

sparklers

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<ll> vii;
typedef long double ld;
typedef pair<ll,ll> pii;
#define F first
#define S second
#define pb push_back
#define eb emplace_back
#define all(v) v.begin(),v.end()
#define pow poww
const ll M=1e6+10;
const ll inf=2e18;
const ll mod=1e9+7;
ll pow(ll x,ll y){
  ll res=1;
  x%=mod; 
  while(y>0){
    if((y&1))
    res*=x,res%=mod;
    x*=x,x%=mod;
    y=(y>>1);
  }
  return res;
}
ll n,t,k;
ld a[M];
bool chk(ld x){
  vector<ld>v,vv;
  for(int i=k;i<n;i++){
    v.pb(((a[i]-a[i-1])/ld(2))-x);
  }
  reverse(all(v));
  for(int i=k-2;i>=0;i--){
    vv.pb(((a[i+1]-a[i])/ld(2))-x);
  }
  reverse(all(vv));
  ld cur=0;
  while(v.size()>0||vv.size()>0){
    if(v.size()>0&&vv.size()>0){
      if(v.back()<vv.back()){
        cur-=v.back();
        v.pop_back();
      }
      else{
        cur-=vv.back();
        vv.pop_back();
      }
    }
    else if(v.size()>0){
      cur-=v.back();
      v.pop_back();
    }
    else{
      cur-=vv.back();
      vv.pop_back();
    }
    if(cur<0){
    return 0;
    }
  }
  return 1;
}
int main(){
  ios_base::sync_with_stdio(0),cin.tie(0);
  int TC=1;
  //cin>>TC;
  while(TC--){
    cin>>n>>k>>t;
    for(int i=0;i<n;i++){
      cin>>a[i];
    }
    ld l=1,r=mod,mid;
    for(int i=0;i<60;i++){
      mid=((l+r)/2);
      if(chk(mid))
      r=mid;
      else
      l=mid;
    }
    ld x=ll(mid);
    if(x!=mid)
    x=x+1;
    ll y=x;
    cout<<fixed<<(y+t-1)/t<<'\n';
  }
  return 0;
}
/*

*/  

• Subtask 1: 0 / 30
• Subtask 2: 0 / 20
• Subtask 3: 0 / 50