1391-check-if-there-is-a-valid-path-in-a-grid.adoc

1391. Check if There is a Valid Path in a Grid

{leetcode}/problems/check-if-there-is-a-valid-path-in-a-grid/[LeetCode - 1391. Check if There is a Valid Path in a Grid ^]

You are given an m x n grid. Each cell of 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.

<img alt="" src="https://assets.leetcode.com/uploads/2020/03/05/main.png" style="width: 450px; height: 708px;" /> You will initially start at the street of the upper-left cell (0, 0). A valid path in the grid is a path that 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: <img alt="" src="https://assets.leetcode.com/uploads/2020/03/05/e1.png" style="width: 455px; height: 311px;" />

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: <img alt="" src="https://assets.leetcode.com/uploads/2020/03/05/e2.png" style="width: 455px; height: 293px;" />

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).

Constraints:

• m == grid.length

• n == grid[i].length

• 1 ⇐ m, n ⇐ 300

• 1 ⇐ grid[i][j] ⇐ 6

思路分析

一刷

link:{sourcedir}/_1391_CheckIfThereIsAValidPathInAGrid.java[role=include]

参考资料