Submission #732835

#	Time	Username	Problem	Language	Result	Execution time	Memory
732835		vjudge1	Beads and wires (APIO14_beads)	C++17	0 / 100	3 ms	4948 KiB

beads

#include<bits/stdc++.h>
using namespace std;
#define all(fl) fl.begin(),fl.end()
#define pb push_back
#define fi first
#define se second
#define for1(i,j,k) for(int i=j;i<=k;i++)
#define for2(i,j,k) for(int i=j;i>=k;i--)
#define for3(i,j,k,l) for(int i=j;i<=k;i+=l)
#define lb lower_bound
#define ub upper_bound
#define sz(a) (int)a.size()
#define gcd __gcd
#define lcm(x,y) x*y/__gcd(x,y)
using pii=pair<int,int>;
using pli=pair<long long,int>;
const int maxn=2e5+9;
vector<pii>a[maxn];
int p[maxn];
const long long inf=-2e9-7;
long long dp[maxn][2];
long long f[maxn][2];
long long g[maxn][2];
void dfs1(int u,int par){
p[u]=par;
dp[u][1]=inf;
dp[u][0]=0;
for (auto v:a[u]){
    if (v.fi==par)continue;
    dfs1(v.fi,u);
    dp[u][0]+=max(dp[v.fi][1]+v.se,dp[v.fi][0]);
}
long long choose=inf,notchoose=0;
for (auto v:a[u]){
    if (v.fi==par)continue;
    g[v.fi][0]=notchoose;
    g[v.fi][1]=choose;
    choose=max(choose+max(dp[v.fi][0],dp[v.fi][1]+v.se),notchoose+dp[v.fi][0]+v.se);
    notchoose=notchoose+max(dp[v.fi][0],dp[v.fi][1]+v.se);
}
reverse(all(a[u]));
choose=inf,notchoose=0;
for (auto v:a[u]){
    if (v.fi==par)continue;
    g[v.fi][1]+=notchoose;
    g[v.fi][0]+=choose;
    choose=max(choose+max(dp[v.fi][0],dp[v.fi][1]+v.se),notchoose+dp[v.fi][0]+v.se);
    notchoose=notchoose+max(dp[v.fi][0],dp[v.fi][1]+v.se);
}
reverse(all(a[u]));
dp[u][1]=choose;
}
signed main(){
    srand(time(0));
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    //freopen(".INP","r",stdin);
    //freopen(".OUT","w",stdout);
    int n;
    cin>>n;
    for1(i,1,n-1){
    int u,v,w;
    cin>>u>>v>>w;
    a[u].pb({v,w});
    a[v].pb({u,w});
    }
    dfs1(1,0);
    long long ans=dp[1][0];
    for1(i,1,n){
    for (auto v:a[i]){
        if (v.fi==p[i]){
           //dfs2(v.fi,i);
           f[v.fi][0]=dp[v.fi][0]-max(dp[i][0],dp[i][1]+v.se);
           f[v.fi][1]=max(g[i][0],g[i][1]);
        }
    }
    long long value=0;
    for (auto v:a[i]){
        if (v.fi==p[i]){
        value+=max(f[v.fi][0],f[v.fi][1]+v.se);
        }
        else {
        value+=max(dp[v.fi][0],dp[v.fi][1]+v.se);
        }
    }
    for1(j,0,sz(a[i])-1){
    for1(k,j+1,sz(a[i])-1){
    long long newvalue=value;
    int v1=a[i][j].fi,v2=a[i][k].fi;
    if (v1==p[i])newvalue-=max(f[v1][0],f[v1][1]+a[i][j].se)-f[v1][0];
    else newvalue-=max(dp[v1][0],dp[v1][1]+a[i][j].se)-dp[v1][0];
    if (v2==p[i])newvalue-=max(f[v2][0],f[v2][1]+a[i][k].se)-f[v2][0];
    else newvalue-=max(dp[v2][0],dp[v2][1]+a[i][k].se)-dp[v2][0];
    newvalue+=a[i][j].se+a[i][k].se;
    ans=max(ans,newvalue);
    }
    }
    }
    cout<<ans;

}

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