Submission #551650

#	Time	Username	Problem	Language	Result	Execution time	Memory
551650		kwongweng	Beads and wires (APIO14_beads)	C++17	28 / 100	1093 ms	5588 KiB

beads

#include <bits/stdc++.h>
using namespace std;
 
#pragma GCC target ("avx2")
#pragma GCC optimization ("Ofast")
#pragma GCC optimization ("unroll-loops")
 
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef long double ld;
typedef pair<ll, ll> pll;
#define FOR(i, a, b) for(int i = a; i < b; i++)
#define ROF(i, a, b) for(int i = a; i >= b; i--)
#define ms memset
#define pb push_back
#define fi first
#define se second
 
ll MOD = 1000000007;
 
ll power(ll base, ll n){
	if (n == 0) return 1;
	if (n == 1) return base;
	ll halfn = power(base, n/2);
	if (n % 2 == 0) return (halfn * halfn) % MOD;
	return (((halfn * halfn) % MOD) * base) % MOD;
}
 
ll inverse(ll n){
	return power(n, MOD-2);
}
 
ll add(ll a, ll b){
	return (a+b) % MOD;
}
 
ll mul(ll a, ll b){
	a %= MOD;
	return (a*b) % MOD;
}
 
ll gcd(ll a, ll b){
    if (a == 1) return 1;
    if (a == 0) return b;
    return gcd(b%a, a);
}
 
const int N = 200001;
vii g[N];
ll dp[N][2];
//dp[i][0] without edge i, with parent of i
//dp[i][1] with the edge
 
void dfs(int u, int p, int W){
    dp[u][0]=0;dp[u][1]=0;
    ll mini=MOD;
    for (ii edge : g[u]){
        int v=edge.fi; int w=edge.se;
        if (v==p) continue;
        dfs(v,u,w);
        dp[u][0]+=max(dp[v][0],dp[v][1]);
        mini=min(mini,dp[v][1]-dp[v][0]-w);
    }
    if (mini!=MOD) dp[u][1]=max(dp[u][0],dp[u][0]-mini+W);
}
void solve(){
    int n; cin >> n;
    FOR(i,0,n-1){
        int u,v,w; cin>>u>>v>>w;
        g[u].pb({v,w}); g[v].pb({u,w});
    }
    ll ans=0;
    FOR(i,1,n+1){
        dfs(i,0,-MOD);
        ans=max(ans,max(dp[i][0],dp[i][1]));
    }
    cout<<ans<<'\n';
    return;
}
 
int main() {
    ios::sync_with_stdio(false);
    int TC = 1;
    //cin >> TC;
    FOR(i, 1, TC+1){
        //cout << "Case #" << i << ": ";
        solve();
    }
}

Compilation message (stderr)

beads.cpp:5: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    5 | #pragma GCC optimization ("Ofast")
      | 
beads.cpp:6: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    6 | #pragma GCC optimization ("unroll-loops")
      |

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