10161. 「一本通 5.2 练习 4」叶子的染色

if(c[x]) f[x][1]=1,f[x][0]=2e9,f[x][2]=1;//如果为白色
else f[x][0]=1,f[x][1]=2e9,f[x][2]=1;//如果为黑色

f[x][1]=1,f[x][0]=1;

#include<algorithm>
#include<bitset>
#include<complex>
#include<deque>
#include<exception>
#include<fstream>
#include<functional>
#include<iomanip>
#include<ios>
#include<iosfwd>
#include<iostream>
#include<istream>
#include<iterator>
#include<limits>
#include<list>
#include<locale>
#include<map>
#include<memory>
#include<new>
#include<numeric>
#include<ostream>
#include<queue>
#include<set>
#include<sstream>
#include<stack>
#include<stdexcept>
#include<streambuf>
#include<string>
#include<typeinfo>
#include<utility>
#include<valarray>
#include<vector>
#include<cctype>
#include<cerrno>
#include<cfloat>
#include<ciso646>
#include<climits>
#include<clocale>
#include<cmath>
#include<csetjmp>
#include<csignal>
#include<cstdarg>
#include<cstddef>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<ctime>
#define ll long long
using namespace std;
inline ll read(){
    ll res=0,f=1;char ch=getchar();
    while(ch<'0'ch>'9'){if(ch=='-') f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9') res=res*10+ch-'0',ch=getchar();
    return res*f;
}
inline void write(ll x){
    if(x<0) putchar('-'),x=-x;
    if(x<10) putchar(x+'0');
    else{
        write(x/10);
        putchar(x%10+'0');
    }
}
ll m,n,c[10010],in[10010],rt,f[10010][5];
vector<ll> v[10010];
void TreeDp(ll x,ll fa){
    if(x<=n){//Leaf
        if(c[x]) f[x][1]=1,f[x][0]=2e9,f[x][2]=1;
        else f[x][0]=1,f[x][1]=2e9,f[x][2]=1;
    }else f[x][1]=1,f[x][0]=1;
    for(ll i=0;i<v[x].size();i++){
        ll to=v[x][i];
        if(to==fa) continue ;
        TreeDp(to,x);
        f[x][0]+=min(f[to][0]-1,min(f[to][1],f[to][2]));
        f[x][1]+=min(f[to][0],min(f[to][1]-1,f[to][2]));
        f[x][2]+=min(f[to][0],min(f[to][1],f[to][2]));
    }
}
int main(){
    m=read();n=read();
    for(ll i=1;i<=n;i++) c[i]=read();
    for(ll i=1;i<=m-1;i++){
        ll x=read(),y=read();
        v[x].push_back(y);
        v[y].push_back(x);
        in[x]++;in[y]++;
        if(rt==0){
            if(in[x]>1) rt=x;
            else if(in[y]>1) rt=y;
        }
    }
    TreeDp(rt,0);
    write(min(f[rt][0],f[rt][1]));putchar('\n');
    return 0;
}