OJ-Problems-Source/HDOJ/4340_autoAC.cpp
2016-09-04 15:55:06 +08:00

70 lines
1.5 KiB
C++

#include<cstdio>
#include<cstring>
#include<iostream>
#include<vector>
#include<string>
#include<set>
#include<algorithm>
#include<map>
#include<iostream>
using namespace std;
const int inf = 100000;
const int maxn = 101;
vector<int> edge[maxn];
int a[maxn],b[maxn];
int f[maxn][2],g[maxn][2];
void dfs(int u,int fa)
{
f[u][0]=0;
g[u][0]=0;
int sz=edge[u].size();
int m1=inf,m2=inf;
bool leaf=true;
for(int i=0;i<sz;i++)
{
int v=edge[u][i];
if(v==fa) continue;
dfs(v,u);
leaf=false;
int tmp=min(f[v][0],g[v][1]);
f[u][0]+=tmp;
m1=min(m1,f[v][1]-tmp);
tmp=min(g[v][0],f[v][1]);
g[u][0]+=tmp;
m2=min(m2,g[v][1]-tmp);
}
if(leaf)
{
f[u][1]=a[u];
f[u][0]=a[u]/2;
g[u][1]=b[u];
g[u][0]=b[u]/2;
}
else
{
f[u][1]=f[u][0] + min(a[u],m1+a[u]/2);
f[u][0]+=a[u]/2;
g[u][1]=g[u][0] + min(b[u],m2+b[u]/2);
g[u][0]+=b[u]/2;
}
}
int main()
{
int n;
while(scanf("%d",&n)!=EOF)
{
for(int i=0;i<=n;i++) edge[i].clear();
for(int i=1;i<=n;i++) scanf("%d",&a[i]);
for(int i=1;i<=n;i++) scanf("%d",&b[i]);
for(int i=1,u,v;i<n;i++)
{
scanf("%d%d",&u,&v);
edge[u].push_back(v);
edge[v].push_back(u);
}
dfs(1,0);
printf("%d\n",min(f[1][1],g[1][1]));
}
return 0;
}