grasshop.cpp

#include <stdio.h>
#define NOT_VISITED 2000
using namespace std;
 
int main(){
	int W, H, SX, SY, EX, EY;
	int HX[8] = {1,1,-1,-1,2,2,-2,-2};
	int HY[8] = {2,-2,2,-2,1,-1,1,-1};
 
 
	while (scanf("%d %d %d %d %d %d", &W, &H, &SX, &SY, &EX, &EY) == 6){
		int QP = 0;
		int QL = 1;
		int QX[1010]; 
		int QY[1010];SX--;SY--;EX--;EY--;
		QX[0] = SX; QY[0] = SY;
		int field[102][102];
		for(int i = 0; i < W; i++){
			for(int j = 0; j < H; j++){
				field[i][j] = NOT_VISITED;
			}
		}
		field[SX][SY] = 0;
 
		int can_finish = -1;
		while(QP < QL){
			for(int i = 0; i < 8; i++){
				int nx = QX[QP] + HX[i];
				int ny = QY[QP] + HY[i];
				if(nx >= 0 && ny >= 0 && nx < W && ny < H && field[nx][ny] == NOT_VISITED){
					field[nx][ny] = field[QX[QP]][QY[QP]] +1;
					QX[QL] = nx;
					QY[QL] = ny;
					QL++;
				}
 
			}
			if(field[EX][EY] != NOT_VISITED){
				can_finish = field[EX][EY];
				break;
			}
			QP++;
		}
		if(can_finish > -1){
			printf("%d\n", can_finish);
		}else{
			printf("impossible\n");
		}
 
	}
 
 
 
	return 0;
}