Submission #393523

#	Time	Username	Problem	Language	Result	Execution time	Memory
393523		JimmyZJX	The Big Prize (IOI17_prize)	C++14	20 / 100	25 ms	3520 KiB

prize

#include <iostream>
#include <fstream>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cassert>
#include <tuple>
#include <queue>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <string>
#include <unordered_set>
#include <unordered_map>
#include <numeric>

using namespace std;

typedef long long LL;
typedef vector<int> Vi;
typedef vector<LL> VL;
typedef vector<bool> Vb;
typedef vector<vector<int>> Vii;

#define forR(i, n) for (int i = 0; i < (n); i++)

Vi ask(int i);

int cntV = 0, N, cntNotV;

int ask_cache[200003][2];
Vi askC(int i) {
	if (ask_cache[i][0] >= 0) {
		return Vi{ ask_cache[i][0], ask_cache[i][1] };
	}
	Vi rs = ask(i);
	ask_cache[i][0] = rs[0]; ask_cache[i][1] = rs[1];
	return rs;
}

int getLeftNonVCnt(int i) {
	int c = 0;
	while (true) {
		if (i >= N) return cntNotV - c;
		Vi rs = askC(i);
		if (rs[0] + rs[1] == cntNotV) {
			// is a V node
			return rs[0] - c;
		} else {
			i++;
			c++;
		}
	}
}

int find_best(int n) {
	N = n;
	memset(ask_cache, -1, sizeof(ask_cache));

	if (n <= 5000) {
		forR(i, n) {
			Vi rs = askC(i);
			if (rs[0] == 0 && rs[1] == 0)
				return i;
		}
	}


	cntV = 0;
	forR(i, 500) {
		Vi rs = askC(i);
		if (rs[0] == 0 && rs[1] == 0) return i;
		cntV = max(cntV, n - rs[0] - rs[1]);
	}

	cntNotV = n - cntV;

	int l = 0;
	for (int t = 1; t <= cntNotV; t++) {
		// goal: get the t-th non-V node
		int r = n - 1; // reuse l

		while (l < r) {
			int mid = (l + r) / 2;
			if (getLeftNonVCnt(mid + 1) >= t) {
				r = mid;
			} else {
				l = mid + 1;
			}
		}
		// l is the t-th non-V node
		assert(getLeftNonVCnt(l) == t - 1);
		Vi rs = askC(l);
		assert(rs[0] + rs[1] <= cntNotV);
		if (rs[0] == 0 && rs[1] == 0) return l;
	}

	return -1;

	//int l = 0, r = n - 1;

	//while (l < r) {
	//	int mid = (l + r) / 2;
	//	Vi rs = ask(mid);
	//	if (rs[0] == rs[1]) return mid;
	//	if (rs[0] == 1) {
	//		r = mid - 1;
	//	} else {
	//		l = mid + 1;
	//	}
	//}

	//return l;
}

#ifdef TEST_LOCAL
Vi _answer{ 2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2,2 };
Vi ask(int i) {
	int n = _answer.size();
	assert(i >= 0 && i < n);
	int l = 0, r = 0;
	for (int j = 0; j < n; j++) {
		if (_answer[j] < _answer[i]) {
			if (j < i) l++; else r++;
		}
	}
	return Vi{ l, r };
}

int main() {
	_answer = Vi(6000, 3);
	_answer[3999] = _answer[5997] = _answer[5998] = 2;
	_answer[5999] = 1;

	auto r = find_best(_answer.size());

	return 0;
}
#endif

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