HDU 1011 Starship Troopers

#include<iostream>
#include<cstdio>
#include<cstring>
#include<vector>
using namespace std;
vector<int>list[124];
int value[124],num[124];
int dp[124][124];
int hash[124];
void DFS( int f ,int M )
{
    int len = list[f].size();
    int t=0;
    t = (num[f]+19)/20;
    for( int i = t ; i<= M ; i++ )
    dp[f][i] = value[f];
    hash[f] = 1;    
    for( int  i = 0 ; i < len ; i ++ )
    {
         if(  hash[list[f][i]] )
         {             
            continue;    
         }     
         DFS( list[f][i] , M  );     
         for( int j = M  ; j >= t ; j-- )
         {
             for( int k = 1 ; k<=M ; k++ )
             {   
                  if((j-k)>=t)
                  if( dp[f][j] < dp[f][j-k] + dp[list[f][i]][k] )
                      dp[f][j] = dp[f][j-k] + dp[list[f][i]][k];        
             }        
         }
         
    }
}
int main(  )
{
   int n , m ,a,b;
   while( scanf( "%d%d",&n ,&m ),m!=-1||n!=-1 )
   {
        memset( dp , 0 ,sizeof( dp ) );
        memset( hash , 0 ,sizeof( hash ) );
       for( int i = 1; i <= n ; i++ )
       {
             list[i].clear();
             scanf( "%d%d",&num[i],&value[i] );        
       }
       for( int i = 1; i < n ; i++ )
       {
           scanf( "%d%d",&a ,&b );
           list[a].push_back( b );
           list[b].push_back( a );        
       }
       if( m ==0  )printf( "0\n" );
       else
       {
           DFS( 1 , m );
           printf( "%d\n",dp[1][m] );
      }
   } 
   return 0;    
} 

这是一道树形DP；树形DP在http://acm.hdu.edu.cn/showproblem.php?pid=1561讲过了，这里就不累叙了；

http://www.cnblogs.com/bo-tao/这里可以看到解法；