ch_5402 Course

Tree grouping backpack model,

That is, each child choose one state tree, state f [x] [y] y represents a maximum value of selected sub-tree rooted at x, how the election has not affected

Note that y> = 1 then x must be selected, i.e., x must chose, y can be selected from its child nodes i.e.

Forests also need to establish a virtual lesson even to the point N + 1 without first lesson

#include<iostream> 
#include<cstdio>

#define ri register int
#define u int

namespace opt {
    
    inline u in() {
        u x(0),f(1);
        char s(getchar());
        while(s<'0'||s>'9') {
            if(s=='-') f=-1;
            s=getchar();
        }
        while(s>='0'&&s<='9') {
            x=(x<<1)+(x<<3)+s-'0';
            s=getchar();
        }
        return x*f;
    }
    
}

using opt::in;

#define NN 305

namespace mainstay {
    
    u N,M,cnt,h[NN],v[NN],id[NN],f[NN][NN];
    
    struct node{
        u to,next;
    }a[NN];
    
    inline void add(const u &x,const u &Y) { 
        A [ ++ CNT] .to = Y, A [CNT] .next = H [X], H [X] = CNT; 
    }   
    
    void DFS ( const U & X) {
         for (RI I (H [ X]); I; I = A [I] .next) { 
            U _y (A [I] .to); 
            DFS (_y); 
            for (RI J (M); J> = . 1 ; - J) {
                 for (RI K ( 0 ); K <= J; ++ K) {// do not understand the words of the book and blue (that is to reverse was true), so too may the positive sequence enumeration 
                    F [X] [J] = :: max STD (F [X] [J], F [X] [JK] + F [_y] [K]); 
                } 
            } 
        } 
        IF (X ^ (N + . 1 )) {
            for(ri i(M);i>=1;--i){
                f[x][i]=f[x][i-1]+v[x];
            }
        }
    }
    
    inline void solve(){
        N=in(),M=in();
        for(ri i(1);i<=N;++i){
            u _a(in()),_b(in());
            v[i]=_b;
            if(_a) add(_a,i);
            else add(N+1,i);
        }
        dfs(N+1);
        std::cout<<f[N+1][M];
    }
    
}

int main() {
    
    //freopen("x.txt","r",stdin);
    std::ios::sync_with_stdio(false);
    mainstay::solve();
    
}