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Submission #31648

# Submission time Handle Problem Language Result Execution time Memory
31648 2017-08-30T12:02:58 Z cheater2k Beads and wires (APIO14_beads) C++14
100 / 100
 300 ms 31596 KB 
#include <bits/stdc++.h>
using namespace std;

const int N = 200010;
const int inf = 1e9;

int n;
int f[N][2], g[N][2];
vector < pair<int,int> > G[N], ch[N];
int ans;

void dfs(int u, int p) {
	for (auto edge: G[u]) if (edge.second != p) {
		dfs(edge.second, u);
		ch[u].push_back(edge);
	}
	f[u][1] = -inf;
	f[u][0] = 0;
	for (auto edge: ch[u]) {
		f[u][0] += max(f[edge.second][0], f[edge.second][1] + edge.first);
	}
	for (auto edge: ch[u]) {
		int mx = f[u][0];
		mx -= max(f[edge.second][0], f[edge.second][1] + edge.first);
		mx += (f[edge.second][0] + edge.first);
		f[u][1] = max(f[u][1], mx);
	}
}

void re_dfs(int u, int p) {
	ans = max(ans, g[u][0] + f[u][0]);
	//cerr << "redfs " << u << ' ' << f[u][0] + g[u][0] << ' ' << f[u][1] + g[u][1] << endl;

	// prepare
	vector <int> L(ch[u].size() + 2, 0); L[0] = -inf;
	vector <int> R(ch[u].size() + 2, 0); R[(int)ch[u].size()] = -inf;

	for (int i = 0; i < (int)ch[u].size(); ++i) {
		pair<int,int> edge = ch[u][i];
		L[i + 1] = max(L[i], f[u][0] - max(f[edge.second][0], f[edge.second][1] + edge.first) + (f[edge.second][0] + edge.first));
	}
	for (int i = (int)ch[u].size() - 1; i >= 0; --i) {
		pair<int,int> edge = ch[u][i];
		R[i] = max(R[i + 1], f[u][0] - max(f[edge.second][0], f[edge.second][1] + edge.first) + (f[edge.second][0] + edge.first));
	}

	// solve
	for (int i = 0; i < (int)ch[u].size(); ++i) {
		int v = ch[u][i].second, w = ch[u][i].first;
		int cost = max(f[v][0], f[v][1] + w);
		int fu0 = f[u][0] - cost;
		int mx = max(L[i], R[i + 1]);
		int fu1 = mx >= 0 ? mx - cost : -inf;
		
		g[v][0] = 0, g[v][1] = -inf;
		// g[v][0]
		g[v][0] = max(g[v][0], fu0 + g[u][0]);
		g[v][0] = max(g[v][0], fu1 + g[u][0] + w);
		g[v][0] = max(g[v][0], fu0 + g[u][1] + w);

		// g[v][1]
		g[v][1] = max(g[v][1], g[u][0] + fu0 + w);

		re_dfs(v, u);
	}
}

int main() {
	ios_base::sync_with_stdio(false); cin.tie(0);
	cin >> n;
	for (int i = 1; i < n; ++i) {
		int u, v, w; cin >> u >> v >> w;
		G[u].push_back(make_pair(w,v)); G[v].push_back(make_pair(w,u));
	}

	dfs(1,1);
	g[1][1] = -inf;
	re_dfs(1,1);

	cout << ans << endl;
}

Subtask #1
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 9728 KB Output is correct
2 Correct 10 ms 9728 KB Output is correct
3 Correct 10 ms 9728 KB Output is correct
4 Correct 10 ms 9728 KB Output is correct
5 Correct 9 ms 9728 KB Output is correct
6 Correct 9 ms 9728 KB Output is correct
7 Correct 9 ms 9728 KB Output is correct
8 Correct 10 ms 9728 KB Output is correct
9 Correct 9 ms 9728 KB Output is correct
10 Correct 10 ms 9728 KB Output is correct
11 Correct 10 ms 9728 KB Output is correct
12 Correct 9 ms 9728 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 9728 KB Output is correct
2 Correct 10 ms 9728 KB Output is correct
3 Correct 10 ms 9728 KB Output is correct
4 Correct 10 ms 9728 KB Output is correct
5 Correct 9 ms 9728 KB Output is correct
6 Correct 9 ms 9728 KB Output is correct
7 Correct 9 ms 9728 KB Output is correct
8 Correct 10 ms 9728 KB Output is correct
9 Correct 9 ms 9728 KB Output is correct
10 Correct 10 ms 9728 KB Output is correct
11 Correct 10 ms 9728 KB Output is correct
12 Correct 9 ms 9728 KB Output is correct
13 Correct 10 ms 9728 KB Output is correct
14 Correct 10 ms 9728 KB Output is correct
15 Correct 10 ms 9728 KB Output is correct
16 Correct 10 ms 9728 KB Output is correct
17 Correct 10 ms 9728 KB Output is correct
18 Correct 10 ms 9728 KB Output is correct
19 Correct 10 ms 9728 KB Output is correct
20 Correct 10 ms 9856 KB Output is correct
21 Correct 10 ms 9728 KB Output is correct
22 Correct 9 ms 9728 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 9728 KB Output is correct
2 Correct 10 ms 9728 KB Output is correct
3 Correct 10 ms 9728 KB Output is correct
4 Correct 10 ms 9728 KB Output is correct
5 Correct 9 ms 9728 KB Output is correct
6 Correct 9 ms 9728 KB Output is correct
7 Correct 9 ms 9728 KB Output is correct
8 Correct 10 ms 9728 KB Output is correct
9 Correct 9 ms 9728 KB Output is correct
10 Correct 10 ms 9728 KB Output is correct
11 Correct 10 ms 9728 KB Output is correct
12 Correct 9 ms 9728 KB Output is correct
13 Correct 10 ms 9728 KB Output is correct
14 Correct 10 ms 9728 KB Output is correct
15 Correct 10 ms 9728 KB Output is correct
16 Correct 10 ms 9728 KB Output is correct
17 Correct 10 ms 9728 KB Output is correct
18 Correct 10 ms 9728 KB Output is correct
19 Correct 10 ms 9728 KB Output is correct
20 Correct 10 ms 9856 KB Output is correct
21 Correct 10 ms 9728 KB Output is correct
22 Correct 9 ms 9728 KB Output is correct
23 Correct 12 ms 10112 KB Output is correct
24 Correct 13 ms 10112 KB Output is correct
25 Correct 13 ms 10112 KB Output is correct
26 Correct 16 ms 10496 KB Output is correct
27 Correct 16 ms 10516 KB Output is correct
28 Correct 15 ms 10496 KB Output is correct
29 Correct 15 ms 10368 KB Output is correct
30 Correct 15 ms 10492 KB Output is correct
31 Correct 16 ms 11136 KB Output is correct

Subtask #4
43.0 / 43.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 9728 KB Output is correct
2 Correct 10 ms 9728 KB Output is correct
3 Correct 10 ms 9728 KB Output is correct
4 Correct 10 ms 9728 KB Output is correct
5 Correct 9 ms 9728 KB Output is correct
6 Correct 9 ms 9728 KB Output is correct
7 Correct 9 ms 9728 KB Output is correct
8 Correct 10 ms 9728 KB Output is correct
9 Correct 9 ms 9728 KB Output is correct
10 Correct 10 ms 9728 KB Output is correct
11 Correct 10 ms 9728 KB Output is correct
12 Correct 9 ms 9728 KB Output is correct
13 Correct 10 ms 9728 KB Output is correct
14 Correct 10 ms 9728 KB Output is correct
15 Correct 10 ms 9728 KB Output is correct
16 Correct 10 ms 9728 KB Output is correct
17 Correct 10 ms 9728 KB Output is correct
18 Correct 10 ms 9728 KB Output is correct
19 Correct 10 ms 9728 KB Output is correct
20 Correct 10 ms 9856 KB Output is correct
21 Correct 10 ms 9728 KB Output is correct
22 Correct 9 ms 9728 KB Output is correct
23 Correct 12 ms 10112 KB Output is correct
24 Correct 13 ms 10112 KB Output is correct
25 Correct 13 ms 10112 KB Output is correct
26 Correct 16 ms 10496 KB Output is correct
27 Correct 16 ms 10516 KB Output is correct
28 Correct 15 ms 10496 KB Output is correct
29 Correct 15 ms 10368 KB Output is correct
30 Correct 15 ms 10492 KB Output is correct
31 Correct 16 ms 11136 KB Output is correct
32 Correct 55 ms 13396 KB Output is correct
33 Correct 52 ms 13560 KB Output is correct
34 Correct 51 ms 13304 KB Output is correct
35 Correct 298 ms 24088 KB Output is correct
36 Correct 300 ms 24216 KB Output is correct
37 Correct 283 ms 24128 KB Output is correct
38 Correct 189 ms 24352 KB Output is correct
39 Correct 177 ms 24340 KB Output is correct
40 Correct 185 ms 24028 KB Output is correct
41 Correct 279 ms 31596 KB Output is correct