# ---
# title: 1391. Check if There is a Valid Path in a Grid
# id: problem1391
# author: Tian Jun
# date: 2020-10-31
# difficulty: Medium
# categories: Depth-first Search, Breadth-first Search
# link: <https://leetcode.com/problems/check-if-there-is-a-valid-path-in-a-grid/description/>
# hidden: true
# ---
# 
# Given a _m_ x _n_ `grid`. Each cell of the `grid` represents a street. The
# street of `grid[i][j]` can be:
# 
#   * **1** which means a street connecting the left cell and the right cell.
#   * **2** which means a street connecting the upper cell and the lower cell.
#   * **3**  which means a street connecting the left cell and the lower cell.
#   * **4** which means a street connecting the right cell and the lower cell.
#   * **5** which means a street connecting the left cell and the upper cell.
#   * **6** which means a street connecting the right cell and the upper cell.
# 
# ![](https://assets.leetcode.com/uploads/2020/03/05/main.png)
# 
# You will initially start at the street of the upper-left cell `(0,0)`. A valid
# path in the grid is a path which starts from the upper left cell `(0,0)` and
# ends at the bottom-right cell `(m - 1, n - 1)`. **The path should only follow
# the streets**.
# 
# **Notice** that you are **not allowed** to change any street.
# 
# Return _true_  if there is a valid path in the grid or _false_ otherwise.
# 
# 
# 
# **Example 1:**
# 
# ![](https://assets.leetcode.com/uploads/2020/03/05/e1.png)
# 
#     
#     
#     Input: grid = [[2,4,3],[6,5,2]]
#     Output: true
#     Explanation: As shown you can start at cell (0, 0) and visit all the cells of the grid to reach (m - 1, n - 1).
#     
# 
# **Example 2:**
# 
# ![](https://assets.leetcode.com/uploads/2020/03/05/e2.png)
# 
#     
#     
#     Input: grid = [[1,2,1],[1,2,1]]
#     Output: false
#     Explanation: As shown you the street at cell (0, 0) is not connected with any street of any other cell and you will get stuck at cell (0, 0)
#     
# 
# **Example 3:**
# 
#     
#     
#     Input: grid = [[1,1,2]]
#     Output: false
#     Explanation: You will get stuck at cell (0, 1) and you cannot reach cell (0, 2).
#     
# 
# **Example 4:**
# 
#     
#     
#     Input: grid = [[1,1,1,1,1,1,3]]
#     Output: true
#     
# 
# **Example 5:**
# 
#     
#     
#     Input: grid = [[2],[2],[2],[2],[2],[2],[6]]
#     Output: true
#     
# 
# 
# 
# **Constraints:**
# 
#   * `m == grid.length`
#   * `n == grid[i].length`
#   * `1 <= m, n <= 300`
#   * `1 <= grid[i][j] <= 6`
# 
# 
## @lc code=start
using LeetCode

## add your code here:
## @lc code=end
