Submission #1049621

#	Time	Username	Problem	Language	Result	Execution time	Memory
1049621		LittleOrange	The Big Prize (IOI17_prize)	C++17	20 / 100	5 ms	2904 KiB

prize

#include "prize.h"
#include<bits/stdc++.h>
using namespace std;
using ll = int;
int find_best(int n) {
	mt19937_64 mt(random_device{}());
	vector<array<ll,2>> mem(n,{-1,-1});
	auto qry = [&](ll i){
		if (mem[i][0]==-1){
			auto a = ask(i);
			mem[i] = {a[0],a[1]};
		}
		return mem[i];
	};
	auto sm = [&](const array<ll,2> &o){return o[0]+o[1];};
	ll cnt = 449;
	vector<ll> a(n);
	iota(a.begin(),a.end(),0);
	shuffle(a.begin(),a.end(),mt);
	ll mx = 0;
	for(ll i = 0;i<cnt;i++){
		mx = max(mx,sm(qry(a[i])));
	}
	ll ans = -1;
	function<void(ll,ll,ll,ll)> dfs;
	dfs = [&](ll l, ll r,ll dl, ll dr){
		if (ans != -1) return;
		if (l == r){
			ans = l;
			return;
		}
		array<ll,2> o = {-1,-1};
		ll m = l+r>>1;
		while(sm(o)!=0&&sm(o)!=mx){
			m = r-l>=2?l+1+mt()%(r-l-1):l+mt()%2;
			o = qry(m);
		}
		if (sm(o)==0) {
			ans = m;
			return;
		}
		if (o[0]-dl>0){
			dfs(l,m-1,dl,o[1]);
		}
		if(o[1]-dr>0){
			dfs(m+1,r,o[0],dr);
		}
	};
	dfs(0,n-1,0,0);
	return ans;
}

Compilation message (stderr)

prize.cpp: In lambda function:
prize.cpp:33:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   33 |   ll m = l+r>>1;
      |          ~^~

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