HDU - 1011（树形dp 背包类型的做法）

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#include <cstdio>#include <cstring>#include <vector>#include <iostream>#include <algorithm>using namespace std;const int inf  = 1000000;const int maxn = 105;struct node{int to,next;}tree[maxn*2];int len,head[maxn],n,m,w[maxn],pos[maxn],temp[maxn];void init(){   memset(head,-1,sizeof(head));   len = 0;}void add_eadge(int u,int v){  tree[len].to = v;  tree[len].next = head[u];  head[u] = len++;}int d[maxn][maxn];void dfs(int root,int f){   for(int i=0;i<w[root];i++)       d[root][i] = 0;   for(int j=w[root];j<=m;j++)       d[root][j] = pos[root];   for(int i =head[root];i!=-1;i=tree[i].next){     if(tree[i].to==f) continue;     int p = tree[i].to;     dfs(p,root);     for(int j=0;j<=m;j++) temp[j]=d[root][j];     for(int j=w[root]+1;j<=m;j++)        for(int k=1;k+w[root]<=j;k++){           d[root][j] = max(d[root][j],d[p][k]+temp[j-k]);     }   }}int main(){    while(scanf("%d %d",&n,&m)==2){       if(n==-1) break;       init();       for(int i=1;i<=n;i++){         int x,y;         scanf("%d %d",&x,&y);         w[i] = x/20 + (x%20==0 ? 0:1);         pos[i] = y;       }       for(int i=1;i<n;i++){         int x,y;         scanf("%d %d",&x,&y);         add_eadge(x,y);         add_eadge(y,x);       }       if(n==0 || m==0){           printf("0\n"); continue;       }       dfs(1,-1);       printf("%d\n",d[1][m]);    }    return 0;}

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