grasshop.c

#include <stdio.h>
 
int Pole[101][101];
 
int FrontaX[100*100*20];
int FrontaY[100*100*20];
int Zac,Kon;
int R,C,Gr,Gc,Lr,Lc,Cc,Cr,T;
int Found;
 
void Skoc(int X, int Y, int Time) {
	if ((X<1) || (X>C) || (Y<1) || (Y>R)) return;
	if ((Pole[X][Y] > Time) || (Pole[X][Y] == -1)) {
		Pole[X][Y]=Time;
		FrontaX[++Kon]=X;
		FrontaY[Kon]=Y;
	};
};
 
int main() {
	int x,y;
 
	while (scanf("%d%d%d%d%d%d",&R,&C,&Gr,&Gc,&Lr,&Lc)==6) {
		for (x=0;x<=R;x++) for (y=0;y<=C;y++) Pole[x][y]=-1;
		if ((Gr==Lr) && (Gc == Lc)) {
			printf("0\n");
		} else {
			FrontaX[0]=Gr;
			FrontaY[0]=Gc;
			Zac=0;
			Kon=0;
			Found=0;
			Pole[Gr][Gc]=0;
			while ((Zac<=Kon) && (Found==0)) {
				Cc = FrontaX[Zac];
				Cr = FrontaY[Zac++];
				T = Pole[Cc][Cr];
//printf("%d %d %d %d %d\n",Cc,Cr,T,Zac,Kon);
				Skoc(Cr+2,Cc+1,T+1);
				Skoc(Cr+2,Cc-1,T+1);
				Skoc(Cr-2,Cc+1,T+1);
				Skoc(Cr-2,Cc-1,T+1);
				Skoc(Cr+1,Cc+2,T+1);
				Skoc(Cr+1,Cc-2,T+1);
				Skoc(Cr-1,Cc+2,T+1);
				Skoc(Cr-1,Cc-2,T+1);
			};
			if (Pole[Lr][Lc] == -1) {
				printf("impossible\n");
			} else {
				printf("%d\n",Pole[Lr][Lc]);
			};
		};
	};
	return 0;
};