#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>;
//using pll=pair<long long,long long>
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];
void dfs1(int u,int par){
p[u]=par;
dp[u][1]=inf;
for (auto v:a[u]){
if (v.fi==par)continue;
dfs1(v.fi,u);
//dp[v.fi][1]+=v.se;
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;
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);
}
dp[u][1]=choose;
}
void dfs2(int u,int par){
f[u][0]=0;
f[u][1]=inf;
for (auto v:a[u]){
if (v.fi==par)continue;
dfs2(v.fi,u);
f[v.fi][1]+=v.se;
f[u][0]+=max(f[v.fi][1],f[v.fi][0]);
}
long long choose=inf,notchoose=0;
for (auto v:a[u]){
if (v.fi==par)continue;
choose=max(choose+max(f[v.fi][0],f[v.fi][1]),notchoose+f[v.fi][0]+v.se);
notchoose=notchoose+max(f[v.fi][0],f[v.fi][1]);
//if (u==1)cout<<choose<<" "<<notchoose<<'\n';
}
f[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);
}
}
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);
}
}
//cout<<f[3][1]<<'\n';
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;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
4 ms |
4948 KB |
Output is correct |
| 3 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 4 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 5 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 6 |
Incorrect |
3 ms |
4948 KB |
Output isn't correct |
| 7 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
4 ms |
4948 KB |
Output is correct |
| 3 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 4 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 5 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 6 |
Incorrect |
3 ms |
4948 KB |
Output isn't correct |
| 7 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
4 ms |
4948 KB |
Output is correct |
| 3 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 4 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 5 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 6 |
Incorrect |
3 ms |
4948 KB |
Output isn't correct |
| 7 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
4 ms |
4948 KB |
Output is correct |
| 3 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 4 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 5 |
Correct |
3 ms |
4948 KB |
Output is correct |
| 6 |
Incorrect |
3 ms |
4948 KB |
Output isn't correct |
| 7 |
Halted |
0 ms |
0 KB |
- |
