Submission #768115

#	Time	Username	Problem	Language	Result	Execution time	Memory
768115		GrindMachine	The Big Prize (IOI17_prize)	C++17	20 / 100	95 ms	336 KiB

prize

// Om Namah Shivaya

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x, y) ((x + y - 1) / (y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i, n) for(int i = 0; i < n; ++i)
#define rep1(i, n) for(int i = 1; i <= n; ++i)
#define rev(i, s, e) for(int i = s; i >= e; --i)
#define trav(i, a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a, b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a, b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*

refs:
edi


f(i+1) > f(i)^2
#of non-lollipops = O(sqrt(n))

just check all non-lollipops for diamond
efficiently find all non-lollipops

*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

#include "prize.h"

pii ask2(int i){
	vector<int> v = ask(i);
	return {v[0],v[1]};
}

int find_best(int n) {
	int mx = -1, pos = -1;

	rep(i,450){
		auto [cl,cr] = ask2(i);
		int cnt = cl+cr;
		if(cnt == 0){
			return i;
		}

		if(cnt > mx){
			mx = cnt;
			pos = i;
		}
	}

	assert(pos != -1);

	// find the closest non-lollipop with ind > i
	// given that the curr pos is a lollipop
	while(true){
		int l = pos, r = n-1;
		auto [fcl,fcr] = ask2(pos);
		int first = -1;

		while(l <= r){
			// is there a lollipop in range [pos,mid]?
			int mid = (l+r) >> 1;
			auto [cl,cr] = ask2(mid);
			int cnt = cl+cr;
			bool ok = false;

			// mid is a lollipop
			if(cnt != mx){
				ok = true;
			}
			else{
				// mid is not a lollipop
				if(cl > fcl){
					ok = true;
				}
			}

			if(ok){
				first = mid;
				r = mid-1;
			}
			else{
				l = mid+1;
			}
		}

		if(first == -1){
			break;
		}

		pos = -1;

		// find the closest pos >= first that is a lollipop
		for(int i = first; i < n; ++i){
			auto [cl,cr] = ask2(i);
			int cnt = cl+cr;
			
			if(cnt == 0){
				return i;
			}

			if(cnt == mx){
				pos = i;
				break;
			}
		}

		if(pos == -1) break;
	}

	// assert(0);
	return -1;
}

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