Swift solution for minesweeper challenge: https://leetcode.com/problems/minesweeper

minesweeper.swift

class Solution {
    func updateBoard(_ board: [[Character]], _ click: [Int]) -> [[Character]] {
        let h = board.count
        let w = board[0].count
        
        var copied = board

        func checkAdjacentPoints(x: Int, y: Int) {
            var numberOfBombs = 0
            
            for i in max(0,x-1)...min(h-1,x+1) {
                for j in max(0,y-1)...min(w-1,y+1) {
                    if i==x, j==y { continue }
                    if copied[i][j] == "M" { numberOfBombs += 1 }
                }
            }
            
            if numberOfBombs == 0 {
                copied[x][y] = "B"
                for i in max(0,x-1)...min(h-1,x+1) {
                    for j in max(0,y-1)...min(w-1,y+1) {
                        if i==x, j==y { continue }
                        if copied[i][j] == "E" { checkAdjacentPoints(x: i, y: j) }
                    }
                }
            } else {
                copied[x][y] = Character("\(numberOfBombs)")
            }
        }
        
        if copied[click[0]][click[1]] == "M" {
            copied[click[0]][click[1]] = "X"
        } else {
            checkAdjacentPoints(x: click[0], y: click[1])
        }
        
        return copied
    }
}