哦，逻辑上有错误。要探索往左和往下的路径，对于某些情况要绕过被彗星砸到的区域，然后往回走，得到最短的路径。


#include <iostream>
#include <vector>
#include <queue>
#include <stack>
#include <string>

using namespace std;


struct Point {
	int x, y, t;
	Point(int xx, int yy, int tt) : x(xx), y(yy), t(tt) {}
};

const int SZ = 400;
const int INF = 100000;

int map[SZ][SZ];
bool visited[SZ][SZ];

bool isQualified(int x, int y) {
	if (x >= 0 && x < SZ && y >= 0 && y < SZ)
		return true;
	return false;
}

void setValue(int x, int y, int t) {
	if (isQualified(x, y))
		map[x][y] = min(map[x][y], t);
}

int main() {
	for (int i = 0; i < SZ; i++)
		for (int j = 0; j < SZ; j++) {
			map[i][j] = INF;
			visited[i][j] = false;
		}

	int m = 0;
	cin >> m;

	for (int i = 0; i < m; i++) {
		int x, y, t;
		cin >> x >> y >> t;
		setValue(x, y, t);
		setValue(x-1, y, t);
		setValue(x+1, y, t);
		setValue(x, y-1, t);
		setValue(x, y+1, t);
	}

	int ans = -1;
	if (map[0][0] == INF) {
		ans = 0;
	}
	else if (map[0][0] == 0) {
		ans = -1;
	}
	else {
		queue<Point> que;
		que.push(Point(0, 0, 0));
		visited[0][0] = true;
		while (!que.empty()) {
			Point point = que.front();
			que.pop();
			int x = point.x;
			int y = point.y;
			int t = point.t;
			if (map[x][y] == INF) {
				ans = t;
				break;
			}
			if (isQualified(x - 1, y) && !visited[x - 1][y] && map[x - 1][y] > (t + 1)) {
				que.push(Point(x - 1, y, t + 1));
				visited[x - 1][y] = true;
			}
			if (isQualified(x, y - 1) && !visited[x][y - 1] && map[x][y - 1] > (t + 1)) {
				que.push(Point(x, y - 1, t + 1));
				visited[x][y - 1] = true;
			}
			if (isQualified(x + 1, y) && !visited[x + 1][y] && map[x + 1][y] > (t + 1)) {
				que.push(Point(x + 1, y, t + 1));
				visited[x + 1][y] = true;
			}
			if (isQualified(x, y + 1) && !visited[x][y + 1] && map[x][y + 1] > (t + 1)) {
				que.push(Point(x, y + 1, t + 1));
				visited[x][y + 1] = true;
			}
		}
	}
	cout << ans << endl;
	return 0;
}

> 用上面的答案是13的也测过了，还是WA。谁有原题的测试数据呀？
> 
> #include <iostream>
> #include <vector>
> #include <queue>
> #include <stack>
> #include <string>
> 
> using namespace std;
> 
> struct Point {
> 	int x, y, t;
> 	Point(int xx, int yy, int tt) : x(xx), y(yy), t(tt) {}
> };
> 
> const int SZ = 400;
> const int INF = 100000;
> 
> int map[SZ][SZ];
> bool visited[SZ][SZ];
> 
> bool isQualified(int x, int y) {
> 	if (x >= 0 && x < SZ && y >= 0 && y < SZ)
> 		return true;
> 	return false;
> }
> 
> void setValue(int x, int y, int t) {
> 	if (isQualified(x, y))
> 		map[x][y] = min(map[x][y], t);
> }
> 
> int main() {
> 	for (int i = 0; i < SZ; i++)
> 		for (int j = 0; j < SZ; j++) {
> 			map[i][j] = INF;
> 			visited[i][j] = false;
> 		}
> 
> 	int m = 0;
> 	cin >> m;
> 
> 	for (int i = 0; i < m; i++) {
> 		int x, y, t;
> 		cin >> x >> y >> t;
> 		setValue(x, y, t);
> 		setValue(x-1, y, t);
> 		setValue(x+1, y, t);
> 		setValue(x, y-1, t);
> 		setValue(x, y+1, t);
> 	}
> 
> 	int ans = -1;
> 	if (map[0][0] == INF) {
> 		ans = 0;
> 	}
> 	else if (map[0][0] == 0) {
> 		ans = -1;
> 	}
> 	else {
> 		queue<Point> que;
> 		que.push(Point(0, 0, 0));
> 		visited[0][0] = true;
> 		while (!que.empty()) {
> 			Point point = que.front();
> 			que.pop();
> 			int x = point.x;
> 			int y = point.y;
> 			int t = point.t;
> 			if (map[x][y] == INF) {
> 				ans = t;
> 				break;
> 			}
> 			if (isQualified(x + 1, y) && !visited[x + 1][y] && map[x + 1][y] > (t + 1)) {
> 				que.push(Point(x + 1, y, t + 1));
> 				visited[x + 1][y] = true;
> 			}
> 			if (isQualified(x, y + 1) && !visited[x][y + 1] && map[x][y + 1] > (t + 1)) {
> 				que.push(Point(x, y + 1, t + 1));
> 				visited[x][y + 1] = true;
> 			}
> 		}
> 	}
> 	cout << ans << endl;
> 	return 0;
> }