蓝桥杯备考：BFS之马的遍历

这道题我们得知道象棋里的马能怎么走,应该是按日字走的

如图，就这么走，我们按基础的bfs遍历一下标记每个格子的最短的路径就行了，没到达的格子就设置为-1

#include <iostream>
#include <queue>
#include <cstring>
using namespace std;
const int N = 410;
int n, m, x, y;
int dict[N][N];
int dx[] = { -2,-1,1,2,2,1,-1,-2 };
int dy[] = { 1,2,2,1,-1,-2,-2,-1 };
typedef pair<int, int> PII;
void bfs() {
	memset(dict, -1, sizeof(dict));
	queue<PII> q;
	q.push({ x,y });
	dict[x][y] = 0;
	while (q.size())
	{
		auto t = q.front();
		q.pop();
		int x = t.first;
		int y = t.second;
		for (int k = 0; k < 8; k++)
		{
			int px = x + dx[k];
			int py = y + dy[k];
			if (px<1 || py<1 || px>n || py>m)continue;
			if (dict[px][py] != -1) continue;
			dict[px][py] = dict[x][y] + 1;
			q.push({ px,py });
		}
	}

}
int main()
{

	cin >> n >> m >> x >> y;
	bfs();
	for (int i = 1; i <= n; i++)
	{
		for (int j = 1; j <= m; j++)
		{
			cout << dict[i][j] << " ";
		}
		cout << endl;
	}





	return 0;
}