hdu 1524 A Chess Game 博弈之，SG函数简单题

A Chess Game

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)

Total Submission(s): 1489 Accepted Submission(s): 679



Problem Description
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
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.



Output
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.



Sample Input

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

Sample Output

WIN
WIN
WIN
LOSE
WIN

Wrong了很多次，，让我万万没想到的是，，竟然是初始化错了。。。

哎，什么时候才能克服这种低级错误。。

代码：

#include <stdio.h>
#include <string.h>
#define MAX 1010
bool graph[MAX][MAX];
int n , sg[MAX] , in[MAX];
int getSG(int index)
{
	if(sg[index] != -1)
	{
		return sg[index] ;
	}
	bool hash[MAX] ;
	memset(hash,false,sizeof(hash)) ;
	for(int i = 0 ; i < n ; ++i)
	{
		if(graph[index][i])
		{
			hash[getSG(i)] = true ;
		}
	}
	for(int i = 0 ; i < MAX; ++i)
	{
		if(!hash[i])
		{
			sg[index] = i ;
			break ;
		}
	}
	return sg[index] ;
}

int main()
{
	while(~scanf("%d",&n))
	{
		memset(graph,false,sizeof(graph)) ; 
		memset(sg,-1,sizeof(sg)) ;
		memset(in,0,sizeof(in)) ;
		for(int i = 0 ; i < n ; ++i)
		{
			int m;
			scanf("%d",&m);
			for(int j = 0 ; j < m ; ++j)
			{
				int temp; ;
				scanf("%d",&temp) ;
				in[temp]++ ;
				graph[i][temp] = true ;
			}
		}
		for(int i = 0 ; i < n ; ++i)
		{
			if(in[i] == 0)
			{
				getSG(i) ;
			}
		}
		int m ;
		while(scanf("%d",&m) && m)
		{
			int ans = 0 ;
			for(int i = 0 ; i < m ; ++i)
			{
				int t ;
				scanf("%d",&t) ;
				ans ^= sg[t] ;
			}
			if(ans)
			{
				puts("WIN") ;
			}
			else
			{
				puts("LOSE") ;
			}
		}
	}
	return 0 ;
}

与君共勉