959. Regions Cut By Slashes

In a N x N grid composed of 1 x 1 squares, each 1 x 1 square consists of a /, \, or blank space. These characters divide the square into contiguous regions.

(Note that backslash characters are escaped, so a \ is represented as "\\".)

Return the number of regions.

Example 1:

Input: [
  " /",
  "/ "
]
Output: 2
Explanation: The 2x2 grid is as follows:
![](https://assets.leetcode.com/uploads/2018/12/15/1.png)

Example 2:

Input: [
  " /",
  "  "
]
Output: 1
Explanation: The 2x2 grid is as follows:
![](https://assets.leetcode.com/uploads/2018/12/15/2.png)

Example 3:

Input: [
  "\\/",
  "/\\"
]
Output: 4
Explanation: (Recall that because \ characters are escaped, "\\/" refers to \/, and "/\\" refers to /\.)
The 2x2 grid is as follows:
![](https://assets.leetcode.com/uploads/2018/12/15/3.png)

Example 4:

Input: [
  "/\\",
  "\\/"
]
Output: 5
Explanation: (Recall that because \ characters are escaped, "/\\" refers to /\, and "\\/" refers to \/.)
The 2x2 grid is as follows:
![](https://assets.leetcode.com/uploads/2018/12/15/4.png)

Example 5:

Input: [
  "//",
  "/ "
]
Output: 3
Explanation: The 2x2 grid is as follows:
![](https://assets.leetcode.com/uploads/2018/12/15/5.png)

Note:

1. 1 <= grid.length == grid[0].length <= 30
2. grid[i][j] is either '/', '\', or ' '.

# @lc code=start
using LeetCode

function regions_by_slashes(grid::Vector{String})
    # Like Problem 200
    function dfs(grid::Matrix{Int}, r, c)
        grid[r, c] = 1
        (r + 1 <= len * 3) && grid[r+1, c] == 0 && dfs(grid, r+1, c)
        (r - 1 > 0) && grid[r-1, c] == 0 && dfs(grid, r-1, c)
        (c + 1 <= len * 3) && grid[r, c+1] == 0 && dfs(grid, r, c+1)
        (c - 1 > 0) && grid[r, c-1] == 0 && dfs(grid, r, c-1)
        nothing
    end
    len = length(grid)
    new_grid = fill(0, len * 3, len * 3)
    res = 0
    for i in 1:len
        for j in 1:len
            if grid[i][j] == '\\'
                new_grid[3 * i - 2, 3 * j - 2] = new_grid[3 * i - 1, 3 * j - 1] = new_grid[3 * i, 3 * j] = 1
            elseif grid[i][j] == '/'
                new_grid[3 * i - 2, 3 * j] = new_grid[3 * i - 1, 3 * j - 1] = new_grid[3 * i, 3 * j - 2] = 1
            end
        end
    end
    for r in 1 : len * 3
        for c in 1 : len * 3
            if new_grid[r, c] == 0
                res += 1
                dfs(new_grid, r, c)
            end
        end
    end
    res
end
# @lc code=end

regions_by_slashes (generic function with 1 method)

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