CH 5402 Course
\(solution:\)
Very routine discussion of a question, use the tree structure shows the relationship between the different courses included (here also point to build a virtual forest into a dozen trees). Then use this concept subtree clever aftereffect eliminated because they contain the DP produced relationship. We make the necessary course before having to go to a pipe in a sub-tree full backpack, then each node to a packet backpack also meet local diffusion of the overall optimal solution to go.
\(code:\)
#include<iostream>
#include<cstdio>
#include<iomanip>
#include<algorithm>
#include<cstring>
#include<cstdlib>
#include<ctime>
#include<cmath>
#include<vector>
#include<queue>
#include<map>
#include<set>
#define ll long long
#define db double
#define rg register int
using namespace std;
int n,m,ff,top;
int a[305];
int f[305][305];
int tou[305];
struct su{
int to,next;
}b[305];
inline int qr(){
register char ch; register bool sign=0; rg res=0;
while(!isdigit(ch=getchar())) if(ch=='-')sign=1;
while(isdigit(ch)) res=res*10+(ch^48),ch=getchar();
return sign?-res:res;
}
inline void add(int x,int y){
b[++top].to=y; b[top].next=tou[x]; tou[x]=top;
}
inline void dfs(int i){
for(rg j=tou[i];j;j=b[j].next){
rg to=b[j].to; dfs(to);
for(rg p=m;p>0;--p)
for(rg q=0;q<p;++q)
f[i][p]=max(f[i][p],f[i][q]+f[to][p-q]);
}if(i)for(rg k=m;k>0;--k)f[i][k]=f[i][k-1]+a[i];
}
int main(){
//freopen(".in","r",stdin);
//freopen(".out","w",stdout);
n=qr(); m=qr();
for(rg i=1;i<=n;++i)
add(qr(),i),a[i]=qr();
dfs(0); printf("%d\n",f[0][m]);
return 0;
}