A Chess Game

Time Limit: 3000MS		Memory Limit: 65536K
Total Submissions: 3551		Accepted: 1440

Let's design a new chess game. There are N positions to hold M chesses in this game. Multiple chesses can be located in the same position. The positions are constituted as a topological graph, i.e. there are directed edges connecting some positions, and no cycle exists. Two players you and I move chesses alternately. In each turn the player should move only one chess from the current position to one of its out-positions along an edge. The game does not end, until one of the players cannot move chess any more. If you cannot move any chess in your turn, you lose. Otherwise, if the misfortune falls on me... I will disturb the chesses and play it again.

Do you want to challenge me? Just write your program to show your qualification!

Input
contains multiple test cases. Each test case starts with a number N (1
<= N <= 1000) in one line. Then the following N lines describe the
out-positions of each position. Each line starts with an integer Xi
that is the number of out-positions for the position i. Then Xi integers
following specify the out-positions. Positions are indexed from 0 to
N-1. Then multiple queries follow. Each query occupies only one line.
The line starts with a number M (1 <= M <= 10), and then come M
integers, which are the initial positions of chesses. A line with number
0 ends the test case.

There
is one line for each query, which contains a string "WIN" or "LOSE".
"WIN" means that the player taking the first turn can win the game
according to a clever strategy; otherwise "LOSE" should be printed.

4

2 1 2

0

1 3

0

1 0

2 0 2

0

4

1 1

1 2

0

0

2 0 1

2 1 1

3 0 1 3

0

WIN

WIN

WIN

LOSE

WIN

Huge input,scanf is recommended.

PKU Monthly,CHEN Shixi(xreborner)

 #include<cstdio>

 #include<vector>

 #include<cstring>

 #include<iostream>

 #define FOR(a,b,c) for(int a=(b);a<(c);a++)

 using namespace std;

 const int N = +;

 int n,m,sg[N];

 vector<int> G[N];

 int dfs(int u) {

     if(sg[u]!=-) return sg[u];

     int vis[N];

     memset(vis,,sizeof(vis));

     FOR(i,,G[u].size())

         vis[dfs(G[u][i])]=;

     for(int i=;;i++)

         if(!vis[i]) return sg[u]=i;

 }

 int main() {

     while(scanf("%d",&n)==) {

         FOR(i,,n) G[i].clear();

         int v;

         FOR(i,,n) {

             scanf("%d",&m);

             FOR(j,,m) {

                 scanf("%d",&v);

                 G[i].push_back(v);

             }

         }

         memset(sg,-,sizeof(sg));

         while(scanf("%d",&m) && m) {

             int ans=,q;

             FOR(i,,m)

                 scanf("%d",&q) , ans^=dfs(q);

             if(ans) puts("WIN"); else puts("LOSE");

         }

     }

     return ;

 }