Submission #734670

#	Time	Username	Problem	Language	Result	Execution time	Memory
734670		Abrar_Al_Samit	Beads and wires (APIO14_beads)	C++17	0 / 100	5 ms	6564 KiB

beads

#include<bits/stdc++.h>
using namespace std;


const int nax = 200005;

vector<pair<int,int>>g[nax];

int dp[nax][2], n;

int solve(int v, int topar, int p = -1) {
	int &ret = dp[v][(topar>0)];
	if(ret!=-1) return ret;
	ret = 0;

	int base = 0;
	for(auto [u, w] : g[v]) if(u!=p) {
		base += solve(u, w, v);
	}

	ret = base;

	if(topar) {
		for(auto [u, w] : g[v]) if(u!=p) {
			ret = max(ret, base - solve(u, w, v) + solve(u, 0, v) + topar + w);
		}
	}

	base = 0;
	int mx1(-1), mx2(-1), mx3(-1);
	int t1, t2, t3;

	for(auto [u, w] : g[v]) if(u!=p) {
		if(w > mx1) {
			mx3 = mx2, mx2 = mx1;
			t3 = t2, t2 = t1;
			mx1 = w, t1 = u;
		} else if(w > mx2) {
			mx3 = mx2, t3 = t2;
			mx2 = w, t2 = u;
		} else if(w > mx3) {
			mx3 = w, t3 = u;
		}
		base += solve(u, 0, v);
	}

	if(mx2>-1) ret = max(ret, base + mx1 + mx2);


	if(g[v].size() > 3 - (v==1)) {
		for(auto [u, w] : g[v]) if(u!=p) {
			if(u!=t1 && u!=t2) {
				int cur = base - solve(u, 0, v) + solve(u, w, v) + mx1 + mx2;
				ret = max(ret, cur);
			} else if(u==t1) {
				int cur = base - solve(u, 0, v) + solve(u, w, v) + mx2 + mx3;
				ret = max(ret, cur);
			} else {
				int cur = base - solve(u, 0, v) + solve(u, w, v) + mx1 + mx3;
				ret = max(ret, cur);
			}
		}
	}
	return ret;
}
void PlayGround() {
	cin>>n;
	for(int i=1; i<n; ++i) {
		int u, v, w;
		cin>>u>>v>>w;
		g[u].emplace_back(v, w);
		g[v].emplace_back(u, w);
	}	

	memset(dp, -1, sizeof dp);
	cout<<solve(1, 0)<<'\n';

	// cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
}
int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	PlayGround();
	return 0;
}

Compilation message (stderr)

beads.cpp: In function 'int solve(int, int, int)':
beads.cpp:31:14: warning: variable 't3' set but not used [-Wunused-but-set-variable]
   31 |  int t1, t2, t3;
      |              ^~
beads.cpp:52:13: warning: 't2' may be used uninitialized in this function [-Wmaybe-uninitialized]
   52 |    if(u!=t1 && u!=t2) {
      |       ~~~~~~^~~~~~~~
beads.cpp:52:4: warning: 't1' may be used uninitialized in this function [-Wmaybe-uninitialized]
   52 |    if(u!=t1 && u!=t2) {
      |    ^~

• Subtask 1: 0 / 13
• Subtask 2: 0 / 15
• Subtask 3: 0 / 29
• Subtask 4: 0 / 43