Submission #592603

#	Time	Username	Problem	Language	Result	Execution time	Memory
592603		hltk	The Big Prize (IOI17_prize)	C++17	90 / 100	100 ms	912 KiB

prize

#include "prize.h"

#include <bits/stdc++.h>

using namespace std;

using pii = pair<int, int>;

map<int, pii> C;

pii m_ask(int i) {
	if (C.count(i)) return C[i];
	auto a = ask(i);
	return C[i] = {a[0], a[1]};
}


// 1, 2, 5, 26, 677

int find_best(int n) {
	if (n <= 1000) {
		for (int i = 0; i < n; ++i) {
			auto [a, b] = m_ask(i);
			if (a + b == 0) {
				return i;
			}
		}
		throw;
	}
	int t = 0;
	for (int i = 0; i < 800; ++i) {
		auto [a, b] = m_ask(i);
		t = max(t, a + b);
	}
	auto check = [&](int i) {
		auto [a, b] = m_ask(i);
		return a + b != t;
	};
	for (int i = 0; i < n; ++i) {
		if (check(i)) {
			auto [a, b] = m_ask(i);
			if (a + b == 0) return i;
		} else {
			auto same = [&](int j) {
				return !check(j) && m_ask(j).second == m_ask(i).second;
			};
			int l = i, r = n - 1;
			while (l < r) {
				int m = (l + r) / 2;
				if (!same(m)) r = m;
				else l = m + 1;
			}
			i = l - 1;
		}
	}
}

Compilation message (stderr)

prize.cpp: In function 'int find_best(int)':
prize.cpp:56:1: warning: control reaches end of non-void function [-Wreturn-type]
   56 | }
      | ^

• Subtask 1: 20 / 20
• Subtask 2: 70 / 80