Gem of the hovercraft problem solution

Gem of the hovercraft problem solution

falsePurple theme,
the main difficulty in a few proven weight <= 3,
but I will not permit, are there any big brother to teach a religion to me,
the rest is very simple, each weight value of x, the sons transfer this weights ranging from over, take the minimum.

#include<bits/stdc++.h>
using namespace std;
const int N=1e4+6;
int n,t1,t2,cnt=0,head[N],f[N][4],minx;
struct edge{int nxt,to;}e[N<<1];
inline void add(int u,int v){e[++cnt].nxt=head[u],e[cnt].to=v,head[u]=cnt;}
inline int read(){
   int T=0,F=1; char ch=getchar();
   while(ch<'0'||ch>'9'){if(ch=='-') F=-1; ch=getchar();}
   while(ch>='0'&&ch<='9') T=(T<<3)+(T<<1)+(ch-48),ch=getchar();
   return F*T;
}
void dfs(int x,int fa){
    f[x][1]=1,f[x][2]=2,f[x][3]=3;
    for(int i=head[x];i;i=e[i].nxt)
        if(e[i].to!=fa){
           dfs(e[i].to,x);
           for(int j=1;j<=3;++j){
               minx=(N<<3);
               for(int k=1;k<=3;++k) if(j!=k) minx=min(minx,f[e[i].to][k]);
               f[x][j]+=minx;
           }
        }
} 
int main(){
    n=read();
    for(int i=1;i<n;++i) t1=read(),t2=read(),add(t1,t2),add(t2,t1);
    dfs(1,0),printf("%d\n",min(min(f[1][1],f[1][2]),f[1][3]));
    return 0;
}