Shohei Yoshida
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Shohei Yoshida's Blog

LeetCode 200. Number of Islands in F#

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Shohei Yoshida
·Aug 29, 2022·

1 min read

URL

leetcode.com/problems/number-of-islands

Code

github.com/syohex/dotnet-study/blob/master/..

let numIslands (grid: char [,]) : int =
    let rows = Array2D.length1 grid
    let cols = Array2D.length2 grid

    let rec fillIsland (grid: char [,]) (row: int) (col: int) : unit =
        grid.[row, col] <- '0'

        if row >= 1 && grid.[row - 1, col] = '1' then
            fillIsland grid (row - 1) col

        if row + 1 < rows && grid.[row + 1, col] = '1' then
            fillIsland grid (row + 1) col

        if col >= 1 && grid.[row, col - 1] = '1' then
            fillIsland grid row (col - 1)

        if col + 1 < cols && grid.[row, col + 1] = '1' then
            fillIsland grid row (col + 1)

        ()

    let mutable ret = 0

    for i in 0 .. (rows - 1) do
        for j in 0 .. (cols - 1) do
            if grid.[i, j] = '1' then
                ret <- ret + 1
                fillIsland grid i j

    ret
 
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