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Submission #561530

# Submission time Handle Problem Language Result Execution time Memory
561530 2022-05-13T05:02:55 Z maximath_1 Beads and wires (APIO14_beads) C++11
100 / 100
 155 ms 32596 KB 
#include <iostream>
#include <vector>
using namespace std;

#define endl "\n"
#define ll long long
const ll inf = 1e9 + 69;
const int MX = 200005;

int n;
ll parw[MX], dp[MX][2][2];
vector<pair<int, ll> > adj[MX];

void dfs(int nw, int bf = -1){
	if(adj[nw].size() == 1 && bf != -1) return;

	ll res = 0ll;
	ll best_par_mid = -inf;
	ll best_mid = -inf, best_mid2 = -inf;
	int best_mid_child, best_mid2_child;
	ll best_nomid = -inf, best_nomid2 = -inf;
	int best_nomid_child, best_nomid2_child;

	for(pair<int, ll> i : adj[nw]) if(i.first != bf){
		int nx = i.first; ll wt = i.second;
		parw[nx] = wt;

		dfs(nx, nw);

		ll nomidv = max(dp[nx][0][0], dp[nx][1][0]), 
		midv = max(dp[nx][0][1], dp[nx][1][1]) - nomidv;
		res += nomidv;

		if(best_par_mid < midv) best_par_mid = midv;

		ll unuse_midv = dp[nx][0][1] + wt - nomidv;
		if(best_mid < unuse_midv){
			best_mid2 = best_mid;
			best_mid2_child = best_mid_child;
			best_mid = unuse_midv;
			best_mid_child = nx;
		}else if(best_mid2 < unuse_midv){
			best_mid2 = unuse_midv;
			best_mid2_child = nx;
		}

		ll unuse_nomidv = dp[nx][0][0] + wt - nomidv;
		if(best_nomid < unuse_nomidv){
			best_nomid2 = best_nomid;
			best_nomid2_child = best_nomid_child;
			best_nomid = unuse_nomidv;
			best_nomid_child = nx;
		}else if(best_nomid2 < unuse_nomidv){
			best_nomid2 = unuse_nomidv;
			best_nomid2_child = nx;
		}
	}

	dp[nw][0][0] = res;
	dp[nw][0][1] = max(res + max(0ll, best_par_mid), res + best_nomid + best_nomid2);
	if(best_mid_child != best_nomid_child)
		dp[nw][0][1] = max(dp[nw][0][1], res + best_nomid + best_mid);
	else
		dp[nw][0][1] = max(dp[nw][0][1], max(res + best_nomid + best_mid2, res + best_nomid2 + best_mid));

	dp[nw][1][0] = res + parw[nw] + best_nomid;
	dp[nw][1][1] = res + parw[nw] + best_mid;

	return;
}

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

	cin >> n; ll tw;
	for(int u, v, i = 1; i < n; i ++){
		cin >> u >> v >> tw;
		adj[u].push_back({v, tw});
		adj[v].push_back({u, tw});
	}

	dfs(1);

	cout << max(dp[1][0][0], dp[1][0][1]) << "\n";
	return 0;
}

Compilation message

beads.cpp: In function 'void dfs(int, int)':
beads.cpp:20:22: warning: variable 'best_mid2_child' set but not used [-Wunused-but-set-variable]
   20 |  int best_mid_child, best_mid2_child;
      |                      ^~~~~~~~~~~~~~~
beads.cpp:22:24: warning: variable 'best_nomid2_child' set but not used [-Wunused-but-set-variable]
   22 |  int best_nomid_child, best_nomid2_child;
      |                        ^~~~~~~~~~~~~~~~~
beads.cpp:61:2: warning: 'best_nomid_child' may be used uninitialized in this function [-Wmaybe-uninitialized]
   61 |  if(best_mid_child != best_nomid_child)
      |  ^~
beads.cpp:61:2: warning: 'best_mid_child' may be used uninitialized in this function [-Wmaybe-uninitialized]

Subtask #1
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 3 ms 5028 KB Output is correct
3 Correct 3 ms 4948 KB Output is correct
4 Correct 3 ms 5036 KB Output is correct
5 Correct 3 ms 4948 KB Output is correct
6 Correct 3 ms 4948 KB Output is correct
7 Correct 3 ms 4948 KB Output is correct
8 Correct 3 ms 5012 KB Output is correct
9 Correct 3 ms 4964 KB Output is correct
10 Correct 3 ms 4948 KB Output is correct
11 Correct 3 ms 4948 KB Output is correct
12 Correct 3 ms 4948 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 3 ms 5028 KB Output is correct
3 Correct 3 ms 4948 KB Output is correct
4 Correct 3 ms 5036 KB Output is correct
5 Correct 3 ms 4948 KB Output is correct
6 Correct 3 ms 4948 KB Output is correct
7 Correct 3 ms 4948 KB Output is correct
8 Correct 3 ms 5012 KB Output is correct
9 Correct 3 ms 4964 KB Output is correct
10 Correct 3 ms 4948 KB Output is correct
11 Correct 3 ms 4948 KB Output is correct
12 Correct 3 ms 4948 KB Output is correct
13 Correct 3 ms 4948 KB Output is correct
14 Correct 3 ms 4948 KB Output is correct
15 Correct 3 ms 4948 KB Output is correct
16 Correct 3 ms 5024 KB Output is correct
17 Correct 3 ms 4948 KB Output is correct
18 Correct 3 ms 4948 KB Output is correct
19 Correct 3 ms 4948 KB Output is correct
20 Correct 3 ms 4948 KB Output is correct
21 Correct 3 ms 4948 KB Output is correct
22 Correct 3 ms 5032 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 3 ms 5028 KB Output is correct
3 Correct 3 ms 4948 KB Output is correct
4 Correct 3 ms 5036 KB Output is correct
5 Correct 3 ms 4948 KB Output is correct
6 Correct 3 ms 4948 KB Output is correct
7 Correct 3 ms 4948 KB Output is correct
8 Correct 3 ms 5012 KB Output is correct
9 Correct 3 ms 4964 KB Output is correct
10 Correct 3 ms 4948 KB Output is correct
11 Correct 3 ms 4948 KB Output is correct
12 Correct 3 ms 4948 KB Output is correct
13 Correct 3 ms 4948 KB Output is correct
14 Correct 3 ms 4948 KB Output is correct
15 Correct 3 ms 4948 KB Output is correct
16 Correct 3 ms 5024 KB Output is correct
17 Correct 3 ms 4948 KB Output is correct
18 Correct 3 ms 4948 KB Output is correct
19 Correct 3 ms 4948 KB Output is correct
20 Correct 3 ms 4948 KB Output is correct
21 Correct 3 ms 4948 KB Output is correct
22 Correct 3 ms 5032 KB Output is correct
23 Correct 6 ms 5460 KB Output is correct
24 Correct 5 ms 5548 KB Output is correct
25 Correct 4 ms 5460 KB Output is correct
26 Correct 7 ms 6072 KB Output is correct
27 Correct 8 ms 6064 KB Output is correct
28 Correct 7 ms 5944 KB Output is correct
29 Correct 6 ms 5680 KB Output is correct
30 Correct 7 ms 5972 KB Output is correct
31 Correct 8 ms 6580 KB Output is correct

Subtask #4
43.0 / 43.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 3 ms 5028 KB Output is correct
3 Correct 3 ms 4948 KB Output is correct
4 Correct 3 ms 5036 KB Output is correct
5 Correct 3 ms 4948 KB Output is correct
6 Correct 3 ms 4948 KB Output is correct
7 Correct 3 ms 4948 KB Output is correct
8 Correct 3 ms 5012 KB Output is correct
9 Correct 3 ms 4964 KB Output is correct
10 Correct 3 ms 4948 KB Output is correct
11 Correct 3 ms 4948 KB Output is correct
12 Correct 3 ms 4948 KB Output is correct
13 Correct 3 ms 4948 KB Output is correct
14 Correct 3 ms 4948 KB Output is correct
15 Correct 3 ms 4948 KB Output is correct
16 Correct 3 ms 5024 KB Output is correct
17 Correct 3 ms 4948 KB Output is correct
18 Correct 3 ms 4948 KB Output is correct
19 Correct 3 ms 4948 KB Output is correct
20 Correct 3 ms 4948 KB Output is correct
21 Correct 3 ms 4948 KB Output is correct
22 Correct 3 ms 5032 KB Output is correct
23 Correct 6 ms 5460 KB Output is correct
24 Correct 5 ms 5548 KB Output is correct
25 Correct 4 ms 5460 KB Output is correct
26 Correct 7 ms 6072 KB Output is correct
27 Correct 8 ms 6064 KB Output is correct
28 Correct 7 ms 5944 KB Output is correct
29 Correct 6 ms 5680 KB Output is correct
30 Correct 7 ms 5972 KB Output is correct
31 Correct 8 ms 6580 KB Output is correct
32 Correct 26 ms 10260 KB Output is correct
33 Correct 27 ms 10188 KB Output is correct
34 Correct 26 ms 10304 KB Output is correct
35 Correct 155 ms 26512 KB Output is correct
36 Correct 146 ms 26572 KB Output is correct
37 Correct 153 ms 26684 KB Output is correct
38 Correct 101 ms 25908 KB Output is correct
39 Correct 96 ms 19504 KB Output is correct
40 Correct 101 ms 25796 KB Output is correct
41 Correct 146 ms 32596 KB Output is correct