HDU 2196 Computer

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<queue>
#include<vector>
#include<map>
using namespace std;
typedef long long LL;
const int INF = 1e9+7;
const int maxn = 10010;
const int MOD = 1e9+7;
struct Node
{
    int e;
    LL w;
    Node(int e=0,LL w=0): e(e), w(w) {}
};
struct node
{
    int index;///
    LL num;///
    node(int index = 0,LL num = 0): index(index), num(num){}
}One[maxn], Tow[maxn];
LL dp[maxn];
vector<vector<Node> >G;

void GetMax(node& A,node& B,node C)
{
    if(A.num < C.num)
        B = A, A = C;
    else if(B.num < C.num)
        B = C;
}

void DFS(int root)
{
    int len = G[root].size();

    for(int i=0; i<len; i++)
    {
        int v = G[root][i].e;
        LL w = G[root][i].w;
        DFS(v);
        GetMax(One[root], Tow[root], node(v,One[v].num+w) );
    }
}

void TreeDp(int root,LL W)
{
    dp[root] = W;

    int flag = 0;
    if(dp[root] > One[root].num)
        flag = 1;
    else
        dp[root] = One[root].num;

    int len = G[root].size();
    for(int i=0; i<len; i++)
    {
        int e = G[root][i].e;
        LL  w = G[root][i].w;

        if(flag == 1)
            TreeDp(e, dp[root]+w);
        else
        {
            if(One[root].index == e)
                TreeDp(e, max(Tow[root].num, W)+w);
            else
                TreeDp(e, dp[root] + w);
        }
    }
}

int main()
{
    int n;
    while( scanf("%d", &n) != EOF)
    {
        G.clear();
        G.resize(n+5);
        memset(dp, 0, sizeof(dp));
        memset(One, 0, sizeof(One));
        memset(Tow, 0, sizeof(Tow));
        for(int i=2; i<=n; i++)
        {
            int e, w;
            scanf("%d %d", &e, &w);
            G[e].push_back(Node(i,w));
        }
        DFS(1);
        TreeDp(1, 0);

        for(int i=1; i<=n; i++)
            printf("%I64d\n", dp[i]);
    }
    return 0;
}
/*

4
1 1
2 1
3 1




*/