Submission #409743

#	Time	Username	Problem	Language	Result	Execution time	Memory
409743		Kerim	Beads and wires (APIO14_beads)	C++17	28 / 100	981 ms	3688 KiB

beads

#include "bits/stdc++.h"
#define MAXN 100009
#define INF 1000000007
#define mp(x,y) make_pair(x,y)
#define all(v) v.begin(),v.end()
#define pb(x) push_back(x)
#define wr cout<<"----------------"<<endl;
#define ppb() pop_back()
#define tr(ii,c) for(__typeof((c).begin()) ii=(c).begin();ii!=(c).end();ii++)
#define ff first
#define ss second
#define my_little_dodge 46
#define debug(x)  cerr<< #x <<" = "<< x<<endl;
using namespace std;

typedef long long ll;
typedef pair<int,int> PII;
template<class T>bool umin(T& a,T b){if(a>b){a=b;return 1;}return 0;}
template<class T>bool umax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
int dp[MAXN][2];
vector<PII>adj[MAXN];
void dfs(int nd,int pr=-1,int w_p=-1){
	dp[nd][0]=0;int mx=-INF,mx1=-INF;
	for(int i=0;i<int(adj[nd].size());i++){
		int to=adj[nd][i].ff;
		int w=adj[nd][i].ss;
		if(to==pr)continue;
		dfs(to,nd,w);
		w+=dp[to][0]-dp[to][1];
		dp[nd][0]+=dp[to][1];
		if(mx<w) mx1=mx,mx=w;
		else umax(mx1,w);
	}
	if(~pr)dp[nd][1]=dp[nd][0]+max(0,mx+w_p);
	else dp[nd][0]+=max(0,mx+mx1);
}
int main(){
    //freopen("file.in", "r", stdin);
    int n;
    scanf("%d",&n);
    for(int i=0;i<n-1;i++){
    	int u,v,w;
		scanf("%d%d%d",&u,&v,&w);
		adj[u].pb(mp(v,w));
		adj[v].pb(mp(u,w));	
    }int ans=0;
    vector<int>roots;
    for(int i=1;i<=n;i++)roots.pb(i);
    random_shuffle(all(roots));
    for(int i=0;i<n;i++){
    	if((double)clock()/CLOCKS_PER_SEC>0.98)break;
		dfs(roots[i]);
		umax(ans,dp[roots[i]][0]);
	}
    printf("%d\n",ans);
	return 0;
}

Compilation message (stderr)

beads.cpp: In function 'int main()':
beads.cpp:40:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~
beads.cpp:43:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   43 |   scanf("%d%d%d",&u,&v,&w);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~

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