Day 17 - Number of Islands

Solution.kt

// https://leetcode.com/explore/challenge/card/30-day-leetcoding-challenge/530/week-3/3302/
class Solution {
    fun numIslands(grid: Array<CharArray>): Int {
        var result = 0
        for (row in grid.indices) {
            for (col in grid[0].indices) {
                if (grid[row][col] == '1') {
                    result += 1
                    dfs(grid, row, col)
                }
            }
        }
        return result
    }
    
    fun dfs(grid: Array<CharArray>, row: Int, col: Int) {
        grid[row][col] = '0'
        
        val moves = arrayOf(intArrayOf(0, 1),
                            intArrayOf(1, 0),
                            intArrayOf(-1, 0),
                            intArrayOf(0, -1))
        
        moves.forEach {
            val newRow = row + it[0]
            val newCol = col + it[1]
            
            if (isValidMove(grid, newRow, newCol)) {
                dfs(grid, newRow, newCol)
            }
        }
    }
    
    fun isValidMove(grid: Array<CharArray>, row: Int, col: Int): Boolean {
        if (row < 0 || row == grid.size || col < 0 || col == grid[0].size) { 
            return false
        }
        if (grid[row][col] == '0') {
            return false
        }
        return true
    }
}