grasshop.cpp

#include <cstdlib>
#include <cstdio>
#include <iostream>
 
using namespace std;
 
class field {
	public:
		int x;
		int y;
		field(){};
};
int main () {
	int matrix [100][100];
	int r, c, gr, gc, lr, lc;
	int free,cur;
	int move;
 
 
	field * desk = new field [10000]; 
	while (scanf("%d%d%d%d%d%d",&r,&c,&gr,&gc,&lr,&lc) == 6) {
		lr--;
		lc--;
		gr--;
		gc--;
		cur = 0;
		free = 1;
 
		move = 1;
		for (int i = 0; i < 100; i++)
			for (int j = 0; j < 100; j++)
				matrix[i][j] = -1;
		matrix[gr][gc] = 0;
		desk[cur].x = gr;
		desk[cur].y = gc;
		while (matrix[lr][lc] == -1 && move) {
			move--;
			if (desk[cur].x+2 < r && 
				desk[cur].y+1 < c && 
				matrix[desk[cur].x+2][desk[cur].y+1] == -1) {
				desk[free].x= desk[cur].x+2;
				desk[free].y= desk[cur].y+1;
				matrix[desk[cur].x+2][desk[cur].y+1] = matrix[desk[cur].x][desk[cur].y]+1;
				free++;
				move++;
			}
			if (desk[cur].x+2 < r && 
				desk[cur].y-1 > -1 && 
				matrix[desk[cur].x+2][desk[cur].y-1] == -1) {
				desk[free].x= desk[cur].x+2;
				desk[free].y= desk[cur].y-1;
				matrix[desk[cur].x+2][desk[cur].y-1] = matrix[desk[cur].x][desk[cur].y]+1;
				free++;
				move++;
			}
			if (desk[cur].x-2 > -1 && 
				desk[cur].y+1 < c && 
				matrix[desk[cur].x-2][desk[cur].y+1] == -1) {
				desk[free].x= desk[cur].x-2;
				desk[free].y= desk[cur].y+1;
				matrix[desk[cur].x-2][desk[cur].y+1] = matrix[desk[cur].x][desk[cur].y]+1;
				free++;
				move++;
			}
			if (desk[cur].x-2 > -1 && 
				desk[cur].y-1 > -1 && 
				matrix[desk[cur].x-2][desk[cur].y-1] == -1) {
				desk[free].x= desk[cur].x-2;
				desk[free].y= desk[cur].y-1;
				matrix[desk[cur].x-2][desk[cur].y-1] = matrix[desk[cur].x][desk[cur].y]+1;
				free++;
				move++;
			}
			if (desk[cur].x-1 > -1 && 
				desk[cur].y+2 < c && 
				matrix[desk[cur].x-1][desk[cur].y+2] == -1) {
				desk[free].x= desk[cur].x-1;
				desk[free].y= desk[cur].y+2;
				matrix[desk[cur].x-1][desk[cur].y+2] = matrix[desk[cur].x][desk[cur].y]+1;
				free++;
				move++;
			}
			if (desk[cur].x-1 > -1 && 
				desk[cur].y-2 > -1 && 
				matrix[desk[cur].x-1][desk[cur].y-2] == -1) {
				desk[free].x= desk[cur].x-1;
				desk[free].y= desk[cur].y-2;
				matrix[desk[cur].x-1][desk[cur].y-2] = matrix[desk[cur].x][desk[cur].y]+1;
				free++;
				move++;
			}
			if (desk[cur].x+1 < r && 
				desk[cur].y+2 < c && 
				matrix[desk[cur].x+1][desk[cur].y+2] == -1) {
				desk[free].x= desk[cur].x+1;
				desk[free].y= desk[cur].y+2;
				matrix[desk[cur].x+1][desk[cur].y+2] = matrix[desk[cur].x][desk[cur].y]+1;
				free++;
				move++;
			}
			if (desk[cur].x+1 < r && 
				desk[cur].y-2 > -1 && 
				matrix[desk[cur].x+1][desk[cur].y-2] == -1) {
				desk[free].x= desk[cur].x+1;
				desk[free].y= desk[cur].y-2;
				matrix[desk[cur].x+1][desk[cur].y-2] = matrix[desk[cur].x][desk[cur].y]+1;
				free++;
				move++;
			}
			cur++;		
		}
/*
		for (int i = 0; i < r; i++){
			for (int j = 0; j < c; j++) {
				if (matrix[i][j] == -1)
					cout << "  ";
				else
					cout << matrix[i][j] << " ";
			}
			cout << endl;
		}
*/
		if (matrix[lr][lc] == -1)
			cout << "impossible" << endl;
		else
			cout << matrix[lr][lc] << endl;
 
 
 
 
 
	}
 
	return 0;
}