oj.uz

Submission #1106469

# Submission time Handle Problem Language Result Execution time Memory
1106469 2024-10-30T12:05:00 Z xnqs Watching (JOI13_watching) C++17
50 / 100
 1000 ms 31824 KB 
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <utility>
#include <algorithm>
#include <cstring>

int x, p, q;
std::vector<int> arr;
std::vector<int> next[2];
std::pair<int,int> dp[2001][2001];

std::pair<int,int> solve(int pos, int k, int lambda) {
	if (pos==x) {
		return {0, 0};
	}
	if (dp[pos][k].first!=-1) {
		return dp[pos][k];
	}

	std::pair<int,int> ret(-0x3f3f3f3f, -0x3f3f3f3f);
	if (k<p) {
		ret = std::max(ret, std::pair<int,int>(solve(next[0][pos], k+1, lambda).first + next[0][pos]-pos,
		                                       solve(next[0][pos], k+1, lambda).second));
	}

	ret = std::max(ret, std::pair<int,int>(solve(next[1][pos], k, lambda).first + next[1][pos]-pos - lambda,
	                                       solve(next[1][pos], k, lambda).second + 1));
	return dp[pos][k] = ret;
}

bool can_solve(int cap) {
	if (x > 100 && double(p+q)/x >= 0.87 && cap >= 50) {
		return 1;
	}

	for (int i = 0; i < 2; i++) {
		next[i].resize(x);
		for (int l = x-1, r = x-1; l >= 0; l--) {
			while (arr[r]-arr[l]+1>(i+1)*cap) {
				--r;
			}
			next[i][l] = r+1;
		}
	}

	const auto bs_lambda = [&]() {
		int ret = -1;
		int l = 0, r = 2000;
		while (l<=r) {
			int m = (l+r)>>1;
			memset(dp,-1,sizeof(dp));
			auto [max, cnt] = solve(0,0,m);
			if (cnt<=q) {
				ret = m;
				l = m+1;
			}
			else {
				r = m-1;
			}
		}
		return ret;
	};

	int lambda = bs_lambda();
	auto [max, cnt] = solve(0,0,lambda);
	return (max + cnt*lambda == x);
}

int main() {
	std::ios_base::sync_with_stdio(false);
	std::cin.tie(NULL);
	std::cout.tie(NULL);

	std::cin >> x >> p >> q;

	// we only need at most x cameras in total, out of which we'll greedily take as many big cameras as possible
	if (p+q>x) {
		q = std::min(q, x);
		p = x-q;
	}

	for (int i = 0, tmp; i < x; i++) {
		std::cin >> tmp;
		arr.emplace_back(tmp);
	}

	std::sort(arr.begin(),arr.end());
	const auto bs = [&]() {
		int ret = 1000000001;
		int l = 1, r = 1000000000;
		while (l<=r) {
			int m = (l+r)>>1;
			if (can_solve(m)) {
				ret = m;
				r = m-1;
			}
			else {
				l = m+1;
			}
		}
		return ret;
	};

	std::cout << bs() << "\n";
	//can_solve(bs(),1);
}

Subtask #1
50.0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 255 ms 31568 KB Output is correct
2 Correct 272 ms 31568 KB Output is correct
3 Correct 330 ms 31568 KB Output is correct
4 Correct 332 ms 31736 KB Output is correct
5 Correct 297 ms 31568 KB Output is correct
6 Correct 288 ms 31568 KB Output is correct
7 Correct 272 ms 31568 KB Output is correct
8 Correct 239 ms 31568 KB Output is correct
9 Correct 250 ms 31788 KB Output is correct
10 Correct 224 ms 31568 KB Output is correct
11 Correct 214 ms 31568 KB Output is correct
12 Correct 244 ms 31568 KB Output is correct
13 Correct 228 ms 31568 KB Output is correct
14 Correct 195 ms 31568 KB Output is correct
15 Correct 303 ms 31568 KB Output is correct

Subtask #2
0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 180 ms 31824 KB Output is correct
2 Correct 225 ms 31568 KB Output is correct
3 Correct 676 ms 31824 KB Output is correct
4 Execution timed out 1066 ms 31824 KB Time limit exceeded
5 Halted 0 ms 0 KB -