grasshop.c

#include <stdio.h>
 
int width,height,fx,fy;
int check[101][101];
 
void rek(int sx, int sy, int step)
{
	static int stepX[] = {1, 2, 2, 1, -1, -2, -2, -1};
	static int stepY[] = {2, 1, -1, -2, -2, -1, 1, 2};	
	int i, nextX, nextY;
 
	check[sx][sy] = step;
	for(i=0; i<8; i++){
		nextX = sx + stepX[i];
		nextY = sy + stepY[i];
		if(nextX < 0 || nextX >= width) continue;
		if(nextY < 0 || nextY >= height) continue;		
		if(check[nextX][nextY] > step+1)
			rek(nextX, nextY, step+1);
	}
 
	return;
}
 
 
int main( int agrc, char * argv[] ) {
 
int sx,sy,i,j;
 
while( scanf("%d %d %d %d %d %d", &width,&height,&sx,&sy,&fx,&fy ) != EOF ) 
 {
	for (i=0; i<101;i++)
  		for (j=0; j<101;j++)
  			check[i][j]=200000000;	
	rek(sx, sy, 0);
	if(check[fx][fy] == 200000000)
		printf("impossible\n");
	else
		printf("%d\n", check[fx][fy]);
 
 }
 
return 0;
}