[CODEVS1090][NOIP2013]加分二叉树（树形dp）

题目描述

题解

代码

#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;
#define LL long long
const int N=35;

int n; LL ans;
int root

,ansroot

;
LL score
,f

;

inline LL dfs(int now,int l,int r){
if (f[now][l][r]!=-1) return f[now][l][r];
if (l==r){
f[now][l][r]=score[l];
root[l][r]=l;
return f[now][l][r];
}
LL lch=0,rch=0,t;
for (int i=l;i<now;++i)
if (lch<(t=dfs(i,l,now-1))){
lch=t;
root[l][now-1]=i;
}
for (int i=now+1;i<=r;++i)
if (rch<(t=dfs(i,now+1,r))){
rch=t;
root[now+1][r]=i;
}
if (!(l<=now-1)) lch=1; if (!(now+1<=r)) rch=1;
f[now][l][r]=lch*rch+score[now];
return f[now][l][r];
}
inline void print(int l,int r){
int now=ansroot[l][r];
printf("%d ",now);
if (l<=now-1) print(l,now-1);
if (now+1<=r) print(now+1,r);
}
int main(){
scanf("%d",&n);
for (int i=1;i<=n;++i) scanf("%I64d",&score[i]);
memset(f,-1,sizeof(f));
for (int i=1;i<=n;++i){
LL t=dfs(i,1,n);
if (t>ans){
ans=t; root[1]
=i;
for (int j=1;j<=n;++j)
for (int k=j;k<=n;++k)
ansroot[j][k]=root[j][k];
}
}
printf("%I64d\n",ans);
print(1,n);
}