Submission #357547

#	Time	Username	Problem	Language	Result	Execution time	Memory
357547		YJU	Sparklers (JOI17_sparklers)	C++14	100 / 100	30 ms	2944 KiB

sparklers

#include<bits/stdc++.h>
#pragma GCC optimize("unroll-loops,no-stack-protector")
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pll;
const ll MOD=1e9+7;
const ll MOD2=998244353;
const ll N=1e6+5;
const ld pi=acos(-1);
const ll INF=(1LL<<60);
#define SQ(i) ((i)*(i))
#define REP(i,n) for(ll i=0;i<n;i++)
#define REP1(i,n) for(ll i=1;i<=n;i++)
#define pb push_back
#define mp make_pair
#define X first
#define Y second
#define setp setprecision
#define lwb lower_bound
#define SZ(_a) (ll)_a.size()
 
ll n,JOI,t,x[N],u[N];
 
bool ck(ll k){
	REP1(i,n)x[i]=u[i]-2*k*t*i;
	ll gl=1,gr=n;
	for(int i=1;i<=JOI;i++)gl=(x[i]>x[gl]?i:gl);
	for(int i=JOI;i<=n;i++)gr=(x[i]<x[gr]?i:gr);
	ll ql=JOI,qr=JOI;
	ll lv=x[ql],rv=x[qr];
	while(ql>=gl||qr<=gr){
		ll bl=ql,br=qr;
		for(;qr<=gr&&lv>=x[qr];qr++)rv=min(rv,x[qr]);
		for(;ql>=gl&&x[ql]>=rv;ql--)lv=max(lv,x[ql]);
		if(bl==ql&&br==qr)return 0;
	}
	ql=1;qr=n;
	lv=x[ql];rv=x[qr];
	while(ql<=gl||qr>=gr){
		ll bl=ql,br=qr;
		for(;qr>=gr&&lv>=x[qr];qr--)rv=min(rv,x[qr]);
		for(;ql<=gl&&x[ql]>=rv;ql++)lv=max(lv,x[ql]);
		if(bl==ql&&br==qr)return 0;
	}
	return 1;
}
 
int main(){
	ios_base::sync_with_stdio(0);cin.tie(0);
	cin>>n>>JOI>>t;
	REP1(i,n)cin>>u[i];
	ll l=-1,r=1e9+10;
	while(r-l>1){
		ll mid=(l+r)>>1;
		if(ck(mid)){
			r=mid;
		}else{
			l=mid;
		}
	}
	cout<<r<<"\n";
	return 0;
}

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