oj.uz

Submission #1106467

# Submission time Handle Problem Language Result Execution time Memory
1106467 2024-10-30T12:04:02 Z xnqs Watching (JOI13_watching) C++17
50 / 100
 1000 ms 32004 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 >= 0.95 && cap >= 15) {
		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 231 ms 31568 KB Output is correct
2 Correct 319 ms 31568 KB Output is correct
3 Correct 223 ms 31580 KB Output is correct
4 Correct 257 ms 31568 KB Output is correct
5 Correct 232 ms 31568 KB Output is correct
6 Correct 318 ms 31736 KB Output is correct
7 Correct 314 ms 31788 KB Output is correct
8 Correct 305 ms 31568 KB Output is correct
9 Correct 293 ms 31568 KB Output is correct
10 Correct 303 ms 31796 KB Output is correct
11 Correct 313 ms 31568 KB Output is correct
12 Correct 313 ms 31568 KB Output is correct
13 Correct 310 ms 31788 KB Output is correct
14 Correct 278 ms 31792 KB Output is correct
15 Correct 292 ms 31568 KB Output is correct

Subtask #2
0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 284 ms 31992 KB Output is correct
2 Correct 226 ms 31788 KB Output is correct
3 Correct 500 ms 32004 KB Output is correct
4 Execution timed out 1064 ms 31824 KB Time limit exceeded
5 Halted 0 ms 0 KB -