(树形DP）Party at Hali-Bula(P3342)

这个题是P2342的升级版

题意：请一伙人来参加PARTY，他们都有上级与下级的关系，因为直属上级与下级之前在一起

          会很不尽，所以要避免这样的情况发生。在满足这样的情况下求能参与PARTY的最多人数。

思路：先对其进行DFS，在其中回塑的时候就从基层开始DP，最后是对其唯一性进行判断

难点：判断唯一性。是大BOSS不能是d[1][0]==d[1][1]，且如果一个结点满足d[k][0]>=d[k][1]时可能就有不唯一性。

      这时就要对其子结点一个一个的进行排查，如果是d[son[k]][1]==d[son[k]][0]就不唯一，其实这样的做法我也不太明白就过了。

#include<iostream>#include<vector>#include<map>#include<string>using namespace std;#define N 222#define inf -1000000000map<string,int> go;int n;vector<int> s[N];int d[N][2];bool is_unique;void dfs(int k){int i,j;//cout<<k<<endl;for (vector<int>::size_type it=0;it<s[k].size();it++){dfs(s[k][it]);}i=0;j=0;for (vector<int>::size_type it=0;it<s[k].size();it++){i+=max(d[s[k][it]][0],d[s[k][it]][1]);j+=d[s[k][it]][0];}d[k][0]=i;d[k][1]=1+j;int cur=0;//这里对是否存在唯一的最优结果进行判断if (is_unique)if (d[k][0]>=d[k][1]) //for (vector<int>::size_type it=0;it<s[k].size();it++){if (d[s[k][it]][1]==d[s[k][it]][0]){is_unique=false;break;}}}int main(){//freopen("C:\in.txt","r",stdin);int i,j,k;string a,b;while (cin>>n,n){int cur=1;memset(d,0,sizeof(d));for (i=1;i<=n;i++)s[i].clear();go.clear();cin>>a;go[a]=cur++;k=n-1;while (k--){cin>>a>>b;if (!go[a])go[a]=cur++;if (!go[b])go[b]=cur++;s[go[b]].insert(s[go[b]].end(),go[a]);}is_unique=true;dfs(1);//for (i=1;i<=n;i++)//cout<<d[i][0]<<' '<<d[i][1]<<endl; int big=max(d[1][1],d[1][0]);if (d[1][1]==d[1][0])is_unique=false;cout<<big<<' ';if (is_unique)cout<<"Yes"<<endl;elsecout<<"No"<<endl;}return 0;}

Party at Hali-Bula

Time Limit: 2000MS Memory Limit: 65536KTotal Submissions: 4291 Accepted: 1546

Description

Dear Contestant,

I'm going to have a party at my villa at Hali-Bula to celebrate my retirement from BCM. I wish I could invite all my co-workers, but imagine how an employee can enjoy a party when he finds his boss among the guests! So, I decide not to invite both an employee and his/her boss. The organizational hierarchy at BCM is such that nobody has more than one boss, and there is one and only one employee with no boss at all (the Big Boss)! Can I ask you to please write a program to determine the maximum number of guests so that no employee is invited when his/her boss is invited too? I've attached the list of employees and the organizational hierarchy of BCM.

Best,
--Brian Bennett

P.S. I would be very grateful if your program can indicate whether the list of people is uniquely determined if I choose to invite the maximum number of guests with that condition.

Input

The input consists of multiple test cases. Each test case is started with a line containing an integern (1 ≤ n ≤ 200), the number of BCM employees. The next line contains the name of the Big Boss only. Each of the followingn-1 lines contains the name of an employee together with the name of his/her boss. All names are strings of at least one and at most 100 letters and are separated by blanks. The last line of each test case contains a single 0.

Output

For each test case, write a single line containing a number indicating the maximum number of guests that can be invited according to the required condition, and a word Yes or No, depending on whether the list of guests is unique in that case.

Sample Input

6JasonJack JasonJoe JackJill JasonJohn JackJim Jill2MingCho Ming0

Sample Output

4 Yes1 No

Source