poj 2599 A funny game 博弈论

思路：无向图，走过的点不能在走。dfs搞定……

再就是后继中有必败点的为必胜点！

代码如下：

 

 1 #include<iostream>

 2 #include<cstdio>

 3 #include<cmath>

 4 #include<algorithm>

 5 #include<vector>

 6 #include<cstring>

 7 using namespace std;

 8 int ans;

 9 vector<int>p[1001];

10 bool vis[1001];

11 int dfs(int n)

12 {

13     for(int i=0;i<p[n].size();i++){

14         if(!vis[p[n][i]]){

15             vis[p[n][i]]=1;

16             if(!dfs(p[n][i])){

17                 ans=p[n][i];

18                 return 1;

19             }

20             vis[p[n][i]]=0;

21         }

22     }

23     return 0;

24 }

25 int main()

26 {

27     int n,m,a,b;

28     while(scanf("%d%d",&n,&m)!=EOF){

29         for(int i=0;i<n;i++) p[i].clear();

30         memset(vis,0,sizeof(vis));

31         for(int i=1;i<n;i++){

32             scanf("%d%d",&a,&b);

33             p[a].push_back(b);

34             p[b].push_back(a);

35         }

36         vis[m]=1;

37         if(dfs(m)) printf("First player wins flying to airport %d\n",ans);

38         else printf("First player loses\n");

39     }

40     return 0;

41 }

View Code