제출 #1083256

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1083256		Math4Life2020	커다란 상품 (IOI17_prize)	C++17	20 / 100	32 ms	876 KiB

prize

// Source: https://usaco.guide/general/io

#include <bits/stdc++.h>
using namespace std;
using ll = long long; using pii = pair<ll,ll>;
#include "prize.h"

map<ll,pii> pts;
ll N;
ll gm;
ll ans = -1;
vector<bool> asked;
const ll C = 500;
ll USED;
ll UMAX = 9000;

vector<int> get(ll x) {
	USED++;
	//assert(USED<UMAX);
	if (USED>UMAX) {
		ll y=0;
		while (1) {
			y++;
		}
	}
	return ask((int)x);
}

int triv(int N1) {
	for (ll i=0;i<N1;i++) {
		vector<int> a0 = get(i);
		if ((a0[0]+a0[1])==0) {
			return i;
		}
	}
	return -1;
}

ll process(ll x) {
	if (!asked[x]) {
		vector<int> a0 = get(x);
		pts[x]={a0[0],a0[1]};
		asked[x]=1;
	}
	ll S = pts[x].first+pts[x].second;
	if (S==0) {
		return x;
	}
	if (S<gm) {
		ll y = -1;
		if (x>0 && !asked[x-1]) {
			y=max(y,process(x-1));
		}
		if (x<(N-1) && !asked[x+1]) {
			y=max(y,process(x+1));
		}
		return y;
	}
	return -1;
}

void query(ll a, ll b) {
	if ((a+1)==b) {
		return;
	}
	if (pts[a].first==pts[b].first) {
		return;
	}
	ll c = (a+b)/2;
	ans=max(ans,process(c));
	if (ans!=-1) {
		return;
	}
	auto A1 = pts.find(a); A1++;
	query(a,(*A1).first);
	auto B1 = pts.find(b); B1--;
	query((*B1).first,b);
}

int find_best(int N0) {
	N=N0;
	USED=0;
	gm=0;
	ans = -1;
	pts.clear();
	asked.clear();
	for (ll i=0;i<N;i++) {
		asked.push_back(0);
	}
	if (N<=C) {
		return triv(N);
	}
	ll r = (N-1)/C;
	for (ll i=1;i<=C;i++) {
		vector<int> a0 = get(i*r);
		asked[i*r]=1;
		pts[i*r]={a0[0],a0[1]};
	}
	for (auto A: pts) {
		pii p0 = A.second;
		gm = max(gm,p0.first+p0.second);
	}
	for (auto A: pts) {
		ll v = process(A.first);
		if (v!=-1) {
			return v;
		}
	}
	if (process(0)!=-1) {
		return 0;
	}
	if (process(N-1)!=-1) {
		return (N-1);
	}
	auto A = pts.begin(); auto B=A; B++;
	vector<pii> qrv;
	do {
		pii pa = (*A).second; pii pb = (*B).second;
		if ((pa.first+pa.second+pb.first+pb.second)==(2*gm)) {
			/*query((*A).first,(*B).first);
			if (ans != -1) {
				return ans;
			}*/
			qrv.push_back({(*A).first,(*B).first});
		}
		A++; B++;
	} while (B != pts.end());
	for (pii p0: qrv) {
		query(p0.first,p0.second);
		if (ans != -1) {
			return ans;
		}
	}
}

컴파일 시 표준 에러 (stderr) 메시지

prize.cpp: In function 'int find_best(int)':
prize.cpp:116:14: warning: control reaches end of non-void function [-Wreturn-type]
  116 |  vector<pii> qrv;
      |              ^~~

• Subtask 1: 20 / 20
• Subtask 2: 0 / 80