제출 #1193633

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1193633		LucaLucaM	커다란 상품 (IOI17_prize)	C++20	20 / 100	24 ms	1992 KiB

prize

#include <iostream>
#include <vector>
#include <algorithm>
#include <cassert>
#include <random>
#include "prize.h"

std::mt19937 rng(123);

std::vector<std::pair<int, int>> memo;

int queries = 0;
int answer = -1;

std::pair<int, int> query(int i) {
	if (memo[i].first != -1) {
		return memo[i];
	}
	queries++;
	assert(queries <= 10000);
	auto aux = ask(i);
	if (aux[0] == 0 && aux[1] == 0) {
		answer = i;
	}
	return memo[i] = std::pair<int, int>{aux[0], aux[1]};
}

int total_less(int i) {
	return query(i).first + query(i).second;
}

int countnonmax;

bool is_max(int i) {
	return total_less(i) == countnonmax;
}

int find_best(int n) {
	memo.resize(n, std::pair<int, int>{-1, -1});

	if (n <= 5000) {
		for (int i = 0; i < n; i++) {
			if (total_less(i) == 0) {
				return i;
			}
		}
	}

	std::vector<int> cand;

	auto get = [&](auto &self, int l, int r, int count) -> void {
		if (count == 0 || l > r) {
			return;
		}

		if (answer != -1) {
			return;
		}

		if (r - l <= 2) {
			for (int i = l; i <= r && count; i++) {
				if (!is_max(i) && answer == -1) {
					cand.push_back(i);
					count--;
				}
			}
			return;
		}

		int mid = (l + r) / 2;
		
		while (l <= r && answer == -1 && !is_max(l)) {
			cand.push_back(l++);
		}
		while (r >= l && answer == -1 && !is_max(r)) {
			cand.push_back(r--);
		}
		if (l > r) {
			return;
		}
		
		int split_left = mid;
		int split_right = mid;
		while (split_left >= l && answer == -1 && !is_max(split_left)) {
			cand.push_back(split_left--);
		}
		while (split_right <= r && answer == -1 && !is_max(split_right)) {
			cand.push_back(split_right++);
		}

		std::pair<int, int> L, SL, SR, R;

		if (answer != -1) {
			return;
		}

		if (rng() % 2 == 0) {
			if (l + 1 < split_left) {
				L = query(l);
				SL = query(split_left);
				self(self, l + 1, split_left - 1, SL.first - L.first);
			}
			if (answer != -1) {
				return;
			}
			if (split_right < r) {
				SR = query(split_right);
				R = query(r);
				self(self, split_right + 1, r - 1, R.first - SR.first);
			}
		} else {
			if (split_right < r) {
				SR = query(split_right);
				R = query(r);
				self(self, split_right + 1, r - 1, R.first - SR.first);
			}
			if (answer != -1) {
				return;
			}
			if (l + 1 < split_left) {
				L = query(l);
				SL = query(split_left);
				self(self, l + 1, split_left - 1, SL.first - L.first);
			}
		}
	};

	int p1 = rng() % n;
	int p2 = rng() % n;
	int p3 = rng() % n;

	countnonmax = std::max({total_less(p1), total_less(p2), total_less(p3)});

	get(get, 0, n - 1, countnonmax);
	if (answer != -1) {
		return answer;
	}
	std::sort(cand.begin(), cand.end());
	cand.erase(std::unique(cand.begin(), cand.end()), cand.end());
	
	for (int i = 0; i < (int) cand.size(); i++) {
		if (total_less(cand[i]) == 0) {
			return cand[i];
		}
	}
}

컴파일 시 표준 에러 (stderr) 메시지

prize.cpp: In function 'int find_best(int)':
prize.cpp:146:1: warning: control reaches end of non-void function [-Wreturn-type]
  146 | }
      | ^

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