Submission #226534

#	Time	Username	Problem	Language	Result	Execution time	Memory
226534		jiahng	Lost in the cycle (IOI19_cycle)	C++17	100 / 100	5 ms	512 KiB

cycle

#include <bits/stdc++.h>
#include "cycle.h"
using namespace std;

typedef long long ll;
typedef pair<ll,ll> pi;
typedef vector <ll> vi;
typedef vector <pi> vpi;
#define f first
#define s second
#define FOR(i,s,e) for(ll i=s;i<=ll(e);++i)
#define DEC(i,s,e) for(ll i=s;i>=ll(e);--i)
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define lbd(x, y) lower_bound(all(x), y)
#define ubd(x, y) upper_bound(all(x), y)
#define aFOR(i,x) for (auto i: x)
#define mem(x,i) memset(x,i,sizeof x)
#define fast ios_base::sync_with_stdio(false),cin.tie(0)

int cur = 0;
ll N;
unordered_map <ll,bool> memo,vis;

bool qry(ll a, bool jumping){
	//set cur to a
	
	if (vis[a] && !jumping){
		//cout<<a<<' ';
		return memo[a];
	}
	
	bool res = jump((a - cur + (ll) 10 * N) % N);
	cur = a;
	
	vis[a] = 1;
	memo[a] = res;
	return res;
}

void check(ll x){
	if (!qry(x+1,0)){
		qry(x, 1);
	}else{
		qry(x + N/2, 1);
	}
}

void escape(int n) {
	N = n;
	memo.clear();
	vis.clear();

	if (N == 2){
		jump(1);
		return;
	}
	
	ll l = 0; ll r = N - 1;
	
	bool f = qry(0,0);

	while (l+1 < r){
		
		//cout<<l<<' '<<r<<'\n';
		
		ll mid = (l+r)/2;
	
		if (qry(mid,0) == f){
			l = mid;
			continue;
			if (mid >= N/2) r = mid;
			else l = mid;
		}else{
			r = mid;
			//f = !f;
		}
	}
	
	//cout<<l<<' ';
	
	if (!qry(l,0)){
		if (qry(l+1,0)) l++;
		else l--;
	}

	//cout<<l<<' ';
	check(l);
}

• Subtask 1: 11 / 11
• Subtask 2: 33 / 33
• Subtask 3: 56 / 56