oj.uz

답안 #984481

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
984481 2024-05-16T17:30:16 Z duckindog Mousetrap (CEOI17_mousetrap) C++17
100 / 100
 869 ms 214356 KB 
#include <bits/stdc++.h>

using namespace std;

const int N = 1'000'000 + 10;
int n, t, m;
vector<int> ad[N];
vector<int> path;
bool inPath[N];

bool dfs1(int u, int p = -1) { 
	inPath[u] = u == t;
	for (const auto& v : ad[u]) { 
		if (v == p) continue;
		inPath[u] |= dfs1(v, u);
	}
	if (inPath[u]) path.push_back(u);
	return inPath[u];
}
int f[N];
void dfs2(int u, int p = -1) { 
	vector<int> best {0, 0};
	for (const auto& v : ad[u]) { 
		if (v == p || inPath[v]) continue;
		dfs2(v, u);
		best.push_back(f[v]);
	}
	sort(best.begin(), best.end(), greater<>());
	f[u] = best.size() + best[1] - 2;
	// cerr << u << " ";
  // for (const auto& x : best) cerr << x << " "; cerr << "\n";
}

int32_t main() { 
	cin.tie(0)->sync_with_stdio(0);

	cin >> n >> t >> m;
	for (int i = 1; i < n; ++i) { 
		int u, v; cin >> u >> v;
		ad[u].push_back(v);
		ad[v].push_back(u);
	}

	dfs1(m);
	
	vector<pair<int, int>> value;
	{
		reverse(path.begin(), path.end());
		path.pop_back();
		
		int it = 0;
		for (const auto& u : path) {
			vector<int> best;
			for (const auto& v : ad[u]) { 
				if (inPath[v]) continue;
				dfs2(v, u);
				best.push_back(f[v]);
			}
			sort(best.begin(), best.end(), greater<>());
			for (const auto& x : best) value.push_back({x, it + 1}); 
			it += 1;
		}
	}
	
	for (int i = 0; i < value.size(); ++i) value[i].first += value.size() - i;

	auto chk = [&](int mid) {
		int it = 0;
		for (const auto& [val, d] : value) { 
			if (it + val > mid) { 
				if (it >= d) return false;
				it += 1;
			}
		}
		return it <= mid;
	};

	int l = 0, r = n * 2, it = 0;
	while (l <= r) { 
		int mid = l + r >> 1;
		if (chk(mid)) r = (it = mid) - 1;
		else l = mid + 1;
	}
	cout << it << "\n";
}

Compilation message

mousetrap.cpp: In function 'int32_t main()':
mousetrap.cpp:65:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   65 |  for (int i = 0; i < value.size(); ++i) value[i].first += value.size() - i;
      |                  ~~^~~~~~~~~~~~~~
mousetrap.cpp:80:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   80 |   int mid = l + r >> 1;
      |             ~~^~~

Subtask #1
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 6 ms 26460 KB Output is correct
2 Correct 6 ms 26460 KB Output is correct
3 Correct 6 ms 24412 KB Output is correct
4 Correct 6 ms 26460 KB Output is correct
5 Correct 6 ms 26456 KB Output is correct
6 Correct 7 ms 26604 KB Output is correct
7 Correct 6 ms 24520 KB Output is correct
8 Correct 6 ms 26460 KB Output is correct
9 Correct 6 ms 24412 KB Output is correct
10 Correct 6 ms 24412 KB Output is correct

Subtask #2
25.0 / 25.0

# 결과 실행 시간 메모리 Grader output
1 Correct 257 ms 66992 KB Output is correct
2 Correct 220 ms 68828 KB Output is correct
3 Correct 837 ms 74320 KB Output is correct
4 Correct 336 ms 51428 KB Output is correct
5 Correct 812 ms 74320 KB Output is correct
6 Correct 808 ms 74320 KB Output is correct

Subtask #3
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 6 ms 26460 KB Output is correct
2 Correct 6 ms 26460 KB Output is correct
3 Correct 6 ms 24412 KB Output is correct
4 Correct 6 ms 26460 KB Output is correct
5 Correct 6 ms 26456 KB Output is correct
6 Correct 7 ms 26604 KB Output is correct
7 Correct 6 ms 24520 KB Output is correct
8 Correct 6 ms 26460 KB Output is correct
9 Correct 6 ms 24412 KB Output is correct
10 Correct 6 ms 24412 KB Output is correct
11 Correct 6 ms 26456 KB Output is correct
12 Correct 6 ms 26460 KB Output is correct
13 Correct 7 ms 26612 KB Output is correct
14 Correct 6 ms 26716 KB Output is correct
15 Correct 6 ms 26604 KB Output is correct
16 Correct 6 ms 26460 KB Output is correct
17 Correct 6 ms 26460 KB Output is correct
18 Correct 7 ms 26456 KB Output is correct
19 Correct 6 ms 26604 KB Output is correct
20 Correct 7 ms 26660 KB Output is correct
21 Correct 6 ms 24412 KB Output is correct
22 Correct 6 ms 26456 KB Output is correct

Subtask #4
35.0 / 35.0

# 결과 실행 시간 메모리 Grader output
1 Correct 6 ms 26460 KB Output is correct
2 Correct 6 ms 26460 KB Output is correct
3 Correct 6 ms 24412 KB Output is correct
4 Correct 6 ms 26460 KB Output is correct
5 Correct 6 ms 26456 KB Output is correct
6 Correct 7 ms 26604 KB Output is correct
7 Correct 6 ms 24520 KB Output is correct
8 Correct 6 ms 26460 KB Output is correct
9 Correct 6 ms 24412 KB Output is correct
10 Correct 6 ms 24412 KB Output is correct
11 Correct 257 ms 66992 KB Output is correct
12 Correct 220 ms 68828 KB Output is correct
13 Correct 837 ms 74320 KB Output is correct
14 Correct 336 ms 51428 KB Output is correct
15 Correct 812 ms 74320 KB Output is correct
16 Correct 808 ms 74320 KB Output is correct
17 Correct 6 ms 26456 KB Output is correct
18 Correct 6 ms 26460 KB Output is correct
19 Correct 7 ms 26612 KB Output is correct
20 Correct 6 ms 26716 KB Output is correct
21 Correct 6 ms 26604 KB Output is correct
22 Correct 6 ms 26460 KB Output is correct
23 Correct 6 ms 26460 KB Output is correct
24 Correct 7 ms 26456 KB Output is correct
25 Correct 6 ms 26604 KB Output is correct
26 Correct 7 ms 26660 KB Output is correct
27 Correct 6 ms 24412 KB Output is correct
28 Correct 6 ms 26456 KB Output is correct
29 Correct 6 ms 26460 KB Output is correct
30 Correct 247 ms 73420 KB Output is correct
31 Correct 243 ms 73300 KB Output is correct
32 Correct 253 ms 138200 KB Output is correct
33 Correct 419 ms 214356 KB Output is correct
34 Correct 820 ms 74496 KB Output is correct
35 Correct 869 ms 74332 KB Output is correct
36 Correct 806 ms 83152 KB Output is correct
37 Correct 827 ms 83156 KB Output is correct
38 Correct 625 ms 84816 KB Output is correct
39 Correct 640 ms 84804 KB Output is correct
40 Correct 602 ms 85088 KB Output is correct