HDOJ 1520 Anniversary party

树状DP入门。每组数据只有一颗树。一开始当二叉做，错了- -！一开始子节点开了1005，后来又试了105，都可以。

重写一遍，邻接表~当初的写法不忍直视。。。

#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#include <cmath>using namespace std;#define N 100005typedef long long LL;struct Tree{    int val;    Tree * next;}e[N], * head[N];int par[N];int v[N];int n;int ptr;void init(){    ptr = 0;    for(int i = 1; i <= n; i++){        par[i] = i;    }    memset(head, NULL, sizeof(head));}void Insert(int x, int y){    par[x] = y;    e[ptr].val = x;    e[ptr].next = head[y];    head[y] = &e[ptr++];}int tdp(int x){    Tree *p;    int ans0 = 0;    int ans1 = v[x];    p = head[x];    while(p != NULL){        ans0 += tdp(p -> val);        Tree *pp = head[p -> val];        while(pp != NULL){            ans1 += tdp(pp -> val);            pp = pp -> next;        }        p = p -> next;    }    return max(ans0, ans1);}int main(){    while(scanf("%d", &n) != EOF){        init();        for(int i = 1; i <= n; i++){            scanf("%d", &v[i]);        }        int x, y;        while(scanf("%d%d", &x, &y), x || y){            Insert(x, y);        }        int root = 0;        for(int i = 1; i <= n; i++){            if(par[i] == i)root = i;        }        printf("%d\n", tdp(root));    }    return 0;}

#include<cstdio>#include<iostream>#include<algorithm>#include<cstring>using namespace std;int n;struct Node{    int par;    int v;    int son[105];//HDOJ数据中子节点105即可    int num;}a[6005];int r[6005];int v[6005];void init (int n){    for(int i=0;i<=n;i++)    {        a[i].par=i;        a[i].v=0;        a[i].num=0;    }}int dfs(int x){    if(v[x]!=0)return r[x];    if(x==0)return 0;    v[x]=1;    if(a[x].num==0){r[x]=a[x].v;return r[x];}    int i0=0,i1=a[x].v;    for(int i=0;i<a[x].num;i++)    {        i0+=dfs(a[x].son[i]);        for(int j=0;j<a[a[x].son[i]].num;j++)        {            i1+=dfs(a[a[x].son[i]].son[j]);        }    }    r[x]=max(i0,i1);    return r[x];}int main(){    while(scanf("%d",&n)!=EOF)    {        memset(v,0,sizeof(v));        init (n);        for(int i=1;i<=n;i++)        {            scanf("%d",&a[i].v);        }        int x,y,k=0;        while(scanf("%d%d",&x,&y),x||y)        {            a[x].par=y;            a[y].son[a[y].num]=x;            a[y].num++;        }        x=1;        while(a[x].par!=x)        {            x=a[x].par;        }        int ans=dfs(x);        printf("%d\n",ans);    }    return 0;}