二叉苹果树

Posted 2020-12-31 lcan

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 using namespace std;
 5 const int maxn=107;
 6 int map[maxn][maxn],l[maxn],r[maxn],a[maxn],f[maxn][maxn];
 7 int n,q;
 8 void buildtree(int u){
 9     for(int i=1;i<=n;i++){
10         if(map[u][i]!=-1){
11             l[u]=i;a[i]=map[u][i];
12             map[u][i]=-1;map[i][u]=-1;
13             buildtree(i);
14             break;
15         }
16     }
17     for(int i=1;i<=n;i++){
18         if(map[u][i]!=-1){
19             r[u]=i;a[i]=map[u][i];
20             map[u][i]=-1;map[i][u]=-1;
21             buildtree(i);
22             break;
23         }
24     }
25 }
26 int DP(int i,int j){
27     if(j==0) return f[i][j]=0;
28     if(l[i]==0&&r[i]==0) return f[i][j]=a[i];
29     if(f[i][j]>0) return f[i][j];
30     for(int k=0;k<=j-1;k++)
31         f[i][j]=max(f[i][j],DP(l[i],k)+DP(r[i],j-k-1)+a[i]);
32     return f[i][j];
33 } 
34 int main(){
35     cin>>n>>q;
36     memset(map,-1,sizeof(map));
37     for(int i=1;i<n;i++){
38         int u,v,w;cin>>u>>v>>w;
39         map[u][v]=w;map[v][u]=w;
40     } 
41     buildtree(1);
42     int ans=DP(1,q+1);
43     cout<<ans<<endl;
44     return 0;
45 }