dp[x][0] 表示 x 節點向下走的最大值
dp[x][1]表示 x 節點向下走的次大值
dp[x][2] 表示 x 節點向上走的最大值
題目鏈接
//#pragma GCC optimize(2)
#include<bits/stdc++.h>
//typedef long long ll;
#define ull unsigned long long
#define int long long
#define F first
#define S second
#define endl "\n"//<<flush
#define eps 1e-6
#define base 131
#define lowbit(x) (x&(-x))
#define PI acos(-1.0)
#define inf 0x3f3f3f3f
#define MAXN 0x7fffffff
#define INF 0x3f3f3f3f3f3f3f3f
#define pa pair<int,int>
#define ferma(a,b) pow(a,b-2)
#define pb push_back
#define all(x) x.begin(),x.end()
#define memset(a,b) memset(a,b,sizeof(a));
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
using namespace std;
void file()
{
#ifdef ONLINE_JUDGE
#else
freopen("D:/LSNU/codeforces/duipai/data.txt","r",stdin);
// freopen("D:/LSNU/codeforces/duipai/AC.txt","w",stdout);
#endif
}
const int N=5e5+5;
vector<pair<int,int> >G[N];
int dp[N][3],pot[N];
void dfs(int u,int fat)
{
for(auto it:G[u])
{
int v=it.F,cost=it.S;
if(v==fat)
continue;
dfs(v,u);
if(dp[u][0]<=dp[v][0]+cost)
{
dp[u][1]=dp[u][0];
dp[u][0]=dp[v][0]+cost;
pot[u]=v;
}
else if(dp[u][1]<dp[v][0]+cost)
dp[u][1]=dp[v][0]+cost;
}
}
void dfs1(int u,int fat)
{
for(auto it:G[u])
{
int v=it.F,cost=it.S;
if(v==fat)
continue;
if(pot[u]==v)
dp[v][2]=cost+max(dp[u][1],dp[u][2]);
else
dp[v][2]=cost+max(dp[u][0],dp[u][2]);
dfs1(v,u);
}
}
signed main()
{
IOS;
// file();
int n;
while(cin>>n)
{
for(int i=2; i<=n; i++)
{
int u,v;
cin>>u>>v;
G[u].pb({i,v});
G[i].pb({u,v});
}
dfs(1,0);
dfs1(1,0);
for(int i=1; i<=n; i++)
cout<<max(dp[i][0],dp[i][2])<<endl,G[i].clear();
memset(dp,0);
memset(pot,0);
}
return 0;
}