Submission #198220

#	Time	Username	Problem	Language	Result	Execution time	Memory
198220		mehrdad_sohrabi	Beads and wires (APIO14_beads)	C++14	28 / 100	1075 ms	888 KiB

beads

#include <bits/stdc++.h>
typedef int ll;
typedef long double ld;
#define pb push_back
#define pii pair < int, int >
#define F first
#define S second
//#define int long long int
#define sync ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#pragma GCC optimize ("Ofast")
#pragma GCC optimize ("unroll-loops")
#define endl '\n'
using namespace std;
const int N=10002;
vector <pii> g[N];
ll vis[N];
ll ans=0;
ll dp[N][2];
void dfs(ll v,ll p,ll w){
    vector <pii> a;
    for (auto u : g[v]){
        if (u.F==p) continue;
        dfs(u.F,v,u.S);
        dp[v][1]+=dp[u.F][0];
        a.pb({dp[u.F][1]+u.S-dp[u.F][0],dp[u.F][0]});
    }
    sort(a.begin(),a.end());
    reverse(a.begin(),a.end());
    if (p!=-1 && a.size()){
        ll cnt=0;
        for (int i=0;i<a.size();i++){
            cnt+=a[i].S;
        }
        cnt+=a[0].F+w;
        dp[v][0]=max(dp[v][1],cnt);
    }
}
int32_t main(){
    sync;
    ll n;
    cin >> n;
    for (int i=0;i<n-1;i++){
        ll u,v,w;
        cin >> u >> v >> w;
        g[u].pb({v,w});
        g[v].pb({u,w});
    }
    for (int i=1;i<=n;i++){
        vector <pii> a;
        for (auto  q : g[i]){
           ll u=q.F;
            if (g[u].size()==1) a.pb({q.S,u});
        }
        sort(a.begin(),a.end());
        for (int j=1;j<a.size();j++){
            vis[a[j].S]=1;
        }
    }
    ll ma=0;
    ll q=1e9,z=1;
    for (int i=1;i<=n;i++){
        if (g[i].size()!=1) continue;
        if (g[i][0].S<q){
            q=g[i][0].S;
            z=i;
        }
    }
    for (int i=1;i<=n;i++){
        if (g[i].size()!=1 && vis[i]!=1) continue;
        memset(vis,0,sizeof vis);
        memset(dp,0,sizeof dp);
        ans=0;
        dfs(i,-1,0);
        ma=max(ma,dp[i][1]);
      //  cout << i << " " << dp[i][1] << endl;
    }
    cout << ma << endl;
}
/*
10
4 10 2
1 2 21
1 3 13
6 7 1
7 9 5
2 4 3
2 5 8
1 6 55
6 8 34
*/
/*
6
1 2 20
2 3 20
3 4
10
3 5 10
3 6 10
*/

Compilation message (stderr)

beads.cpp: In function 'void dfs(ll, ll, ll)':
beads.cpp:31:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i=0;i<a.size();i++){
                      ~^~~~~~~~~
beads.cpp: In function 'int32_t main()':
beads.cpp:55:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int j=1;j<a.size();j++){
                      ~^~~~~~~~~
beads.cpp:60:14: warning: variable 'z' set but not used [-Wunused-but-set-variable]
     ll q=1e9,z=1;
              ^

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