馬踏棋盤

#include<stdio.h>
#include<time.h>

#define X 8
#define Y 8

int chess[X][Y];

void print(void);
//找到基於（x,y）位置的下一個可走的位置
int nextxy(int *x,int *y ,int count)
{
	switch(count)
	{
		case 0:
			if(*x+2<=X-1&&*y-1>=0&&chess[*x+2][*y-1] == 0)
			{
				*x += 2;
				*y -= 1;
				return 1;
			}
			break;
		case 1:
			if(*x+2<=X-1&&*y+1<=Y-1&&chess[*x+2][*y+1] == 0)
			{
				*x +=2;
				*y +=1;
				return 1;
			}
			break;

		case 5:
			if(*x-2>=0&&*y+1<=Y-1&&chess[*x-2][*y+1] == 0)
			{
				*x -=2;
				*y +=1;
				return 1;
			}
			break;
		case 4:
			if(*x-2>=0&&*y-1>=0&&chess[*x-2][*y-1] == 0)
			{
				*x -=2;
				*y -=1;
				return 1;
			}
			break;
		case 3:
			if(*x+1<=X-1&&*y+2<=Y-1&&chess[*x+1][*y+2] == 0)
			{
				*x +=1;
				*y +=2;
				return 1;
			}
			break;
		case 2:
			if(*x+1<=X-1&&*y-2>=0&&chess[*x+1][*y-2] == 0)
			{
				*x +=1;
				*y -=2;
				return 1;
			}
			break;
		case 7:
			if(*x-1>=0&&*y+2<=Y-1&&chess[*x-1][*y+2] == 0)
			{
				*x -=1;
				*y +=2;
				return 1;
			}
			break;
		case 6:
			if(*x-1>=0&&*y-2>=0&&chess[*x-1][*y-2] == 0)
			{
				*x -=1;
				*y -=2;
				return 1;
			}
			break;
		default:
			break;
	}
	return 0;
}
//深度優先便利棋盤
//（x,y）爲位置座標
//tag是標記變量，每走一部tag+1
int TravelChessBoard(int x,int y,int tag)
{
	int x1 = x,y1 = y,flag = 0,count = 0;
	chess[x][y] = tag;
	if(X*Y == tag)
	{
		//打印棋盤
		print();
		return 1;
	}
	//找到馬的下一個可走的座標（x1,y1）如果找到flag = 1,否則爲0
	flag = nextxy(&x1,&y1,count);
	while(0 == flag&& count<7)
	{
		count++;
		flag = nextxy(&x1,&y1,count);
	}
	while(flag)
	{
		if(TravelChessBoard(x1,y1,tag+1))
		{
			return 1;
		}
		//繼續找找到馬的下一步可以走的座標（x1,y1）,否則爲0
		x1 = x;
		y1 = y;
		count ++;

		flag = nextxy(&x1,&y1,count);
		while(0 == flag &&count<7)
		{
			count++;
			flag = nextxy(&x1,&y1,count);
		}
	}
	if(0 == flag)
	{
		chess[x][y] = 0;
	}
	return 0;
}
void print(void)
{
	int i,j;
	for(i = 0;i<X;i++)
	{
		for(j=0;j<Y;j++)
		{
			printf("%2d\t",chess[i][j]);
		}
		printf("\n");
	}
	printf("\n");
}




int main()
{
	int i,j;
	clock_t start,finish;
	start = clock();
	for(i = 0;i<X;i++)
	{
		for(j = 0;j<Y;j++)
		{
			chess[i][j] = 0;
		}
	}
	if(!TravelChessBoard(2,0,1))
	{
		printf("sorry fail\n");
	}
	finish = clock();
	printf("time is %f second",(double)(finish-start)/CLOCKS_PER_SEC);
	return 0;
}