Submission #344444

#	Time	Username	Problem	Language	Result	Execution time	Memory
344444		wwdd	Beads and wires (APIO14_beads)	C++14	0 / 100	1 ms	896 KiB

beads

//gross
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<ll> vl;
typedef pair<ll,ll> pl;
typedef vector<pl> vpl;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<vpl> al;
struct EG {
	ll st,ed,wo;
};
const ll INFL = 1e18;
const int MN = 200200;
ll dp[MN][2];
bool bp[MN][2];
vl lev;
vvi g;
void dfa(int u, int p) {
	if(u != p) {
		lev[u] = lev[p]+1;
	}
	for(int i=0;i<g[u].size();i++) {
		int v = g[u][i];
		if(v == p) {continue;}
		dfa(v,u);
	}
}
vl ko;
ll ds(int u, int p, int m) {
	if(bp[u][m]) {
		return dp[u][m];
	}
	ll res;
	if(m) {
		if(g[u].size() >= 1) {
			res = 0;
			ll ma = -INFL;
			for(int i=0;i<g[u].size();i++) {
				int v = g[u][i];
				if(v == p) {continue;}
				ll mv = max(ko[v]+ds(v,u,1),ds(v,u,0));
				res += mv;
				ma = max(ma,ko[v]+ds(v,u,0)-mv);
			}
			res += ma;
		} else {
			res = -INFL;
		}
	} else {
		res = 0;
		vl du;
		for(int i=0;i<g[u].size();i++) {
			int v = g[u][i];
			if(v == p) {continue;}
			ll mv = max(ds(v,u,0),ko[v]+ds(v,u,1));
			res += mv;
			du.push_back(ko[v]+ds(v,u,0)-mv);
		}
		if(du.size() >= 2) {
			sort(du.rbegin(),du.rend());
			if(du[0]+du[1] >= 0) {
				res += du[0]+du[1];
			}
		}
	}
	bp[u][m] = true;
	return dp[u][m] = res;
}
int main() {
	ios::sync_with_stdio(0);cin.tie(0);
	memset(bp,0,sizeof(bp));
	ll n;
	cin >> n;
	lev.assign(n,0);
	g.assign(n,vi());
	ko.assign(n,0);
	vector<EG> el;
	for(int i=1;i<n;i++) {
		ll a,b,c;
		cin >> a >> b >> c;
		a--;b--;
		g[a].push_back(b);
		g[b].push_back(a);
		el.push_back({a,b,c});
	}
	dfa(0,0);
	for(int i=0;i<el.size();i++) {
		ll a = el[i].st;
		ll b = el[i].ed;
		if(lev[a] > lev[b]) {swap(a,b);}
		ko[b] = el[i].wo;
	}
	cout << ds(0,0,0) << '\n';
}

Compilation message (stderr)

beads.cpp: In function 'void dfa(int, int)':
beads.cpp:24:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |  for(int i=0;i<g[u].size();i++) {
      |              ~^~~~~~~~~~~~
beads.cpp: In function 'll ds(int, int, int)':
beads.cpp:40:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   40 |    for(int i=0;i<g[u].size();i++) {
      |                ~^~~~~~~~~~~~
beads.cpp:54:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |   for(int i=0;i<g[u].size();i++) {
      |               ~^~~~~~~~~~~~
beads.cpp: In function 'int main()':
beads.cpp:89:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<EG>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   89 |  for(int i=0;i<el.size();i++) {
      |              ~^~~~~~~~~~

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