1009.cpp

哈尔滨工业大学ACM 竞赛网上在线试题集锦的源代码

/*  This Code is Submitted by wywcgs for Problem 1009 on 2005-12-09 at 00:02:45 */ 
#include <cstdio>

const int MAX = 128;

int map[MAX][MAX];
int max, bx, by;
bool eat;

inline int abs(int);
void move(int, int);

int main()
{
	int n, m, i, j;
	int cx, cy, d;
		
	while(scanf("%d %d", &n, &m) != EOF) {
		for(i = 0; i < n; i++) {
			for(j = 0; j < m; j++) {
				scanf("%d", &map[i][j]);
			}
		}
		scanf("%d %d", &cx, &cy);
		int mx = 0, my = 0;
		int esc = false;
		for(d = 0; true; d++) {
			map[mx][my] = 0;
			if(abs(cx-mx)+abs(cy-my) <= d) {
				break;
			} else {
				eat = false;
				max = 0;
				if(mx > 0)    move(mx-1, my);
				if(mx < n-1)  move(mx+1, my);
				if(my > 0)    move(mx, my-1);
				if(my < m-1)  move(mx, my+1);
				if(!eat) {
					esc = true;
					break;
				} else {
					mx = bx;
					my = by;
					
				}
			}
		}
		if(esc) {
			printf("impossible\n");
		} else {
			printf("%d\n", d);
		}
	}
	
	return 0;
}

inline int abs(int a)
{
	return a > 0 ? a : -a;
}
void move(int x, int y)
{
	if(map[x][y] > max) {
		bx = x;
		by = y;
		max = map[x][y];
		eat = true;
	}
}