oj.uz

Submission #1106462

# Submission time Handle Problem Language Result Execution time Memory
1106462 2024-10-30T11:50:16 Z xnqs Watching (JOI13_watching) C++17
50 / 100
 1000 ms 12024 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][727];

std::pair<int,int> solve(int pos, int k, int lambda) {
	if (pos==x) {
		return {0, 0};
	}
	if (dp[pos][k].second!=-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) {
	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 = 5000;
		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 62 ms 11600 KB Output is correct
2 Correct 80 ms 11600 KB Output is correct
3 Correct 63 ms 11600 KB Output is correct
4 Correct 74 ms 11600 KB Output is correct
5 Correct 61 ms 11600 KB Output is correct
6 Correct 63 ms 11848 KB Output is correct
7 Correct 78 ms 11600 KB Output is correct
8 Correct 67 ms 11600 KB Output is correct
9 Correct 66 ms 11600 KB Output is correct
10 Correct 80 ms 11600 KB Output is correct
11 Correct 89 ms 11852 KB Output is correct
12 Correct 73 ms 11600 KB Output is correct
13 Correct 74 ms 11600 KB Output is correct
14 Correct 60 ms 11824 KB Output is correct
15 Correct 62 ms 11600 KB Output is correct

Subtask #2
0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 62 ms 11856 KB Output is correct
2 Correct 62 ms 11600 KB Output is correct
3 Execution timed out 1066 ms 12024 KB Time limit exceeded
4 Halted 0 ms 0 KB -