poj 3342 Party at Hali-Bula(트리 dp)

#include<iostream>
#include<algorithm>
#include<vector>
#include<cstdio>
#include<cstring>
#include<string>
#include<map>
using namespace std;

const int maxn = 201;
int dp[maxn][2], num[maxn][2], n, cnt;
map<string, int> s;
vector<int> G[maxn];

int id(string a)
{
    if(s.count(a))  return s[a];
    else    s[a] = cnt++;
    return cnt - 1;
}

void dfs(int u)
{
    dp[u][0] = 0;
    num[u][0] = num[u][1] = dp[u][1] = 1;
    int nc = G[u].size();
    for(int i=0; i<nc; i++)
    {
        int v = G[u][i];
        dfs(v);
        if(dp[v][1] || dp[v][0])
        {
            dp[u][0] += max(dp[v][1], dp[v][0]);
            if(dp[v][1] == dp[v][0])    num[u][0]++;
            else if(dp[v][1] > dp[v][0] && num[v][1] > 1)   num[u][0]++;
            else if(dp[v][0] > dp[v][1] && num[v][0] > 1)   num[u][0]++;
        }
        if(dp[v][0])
        {
            dp[u][1] += dp[v][0];
            if(num[v][0] > 1)   num[u][1]++;
        }
    }
}

int main()
{
    while(cin>>n, n)
    {
        for(int i=0; i<=n; i++) G[i].clear();    s.clear();    cnt = 0;

        string a, b;
        int rt, aa, bb;

        cin>>a;
        rt = id(a);

        for(int i=1; i<n; i++)
        {
            cin>>a>>b;
            aa = id(a); bb = id(b);
            G[bb].push_back(aa);
        }

        dfs(rt);

        int flag;
        if(dp[0][0] == dp[0][1])  flag = num[0][1] + num[0][0];
        else if(dp[0][0] > dp[0][1])  flag = num[0][0];
        else flag = num[0][1];

        int ans = max(dp[0][0], dp[0][1]);
        cout<<ans<<" ";

        if(flag > 1)    cout<<"No"<<endl;
        else    cout<<"Yes"<<endl;
    }
    return 0;
}