g0101_0200.s0200_number_of_islands.Solution.swift Maven / Gradle / Ivy

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104 LeetCode algorithm problem solutions

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// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #Array #Depth_First_Search
// #Breadth_First_Search #Matrix #Union_Find
// #Algorithm_II_Day_6_Breadth_First_Search_Depth_First_Search
// #Graph_Theory_I_Day_1_Matrix_Related_Problems #Level_1_Day_9_Graph/BFS/DFS #Udemy_Graph
// #Big_O_Time_O(M*N)_Space_O(M*N) #2024_07_04_Time_152_ms_(70.92%)_Space_19.2_MB_(44.62%)

class Solution {
    func numIslands(_ grid: [[Character]]) -> Int {
        var grid = grid
        var islands = 0

        if !grid.isEmpty && !grid[0].isEmpty {
            for i in 0..= grid.count || y < 0 || y >= grid[0].count || grid[x][y] != "1" {
            return
        }

        grid[x][y] = "x"
        dfs(&grid, x + 1, y)
        dfs(&grid, x - 1, y)
        dfs(&grid, x, y + 1)
        dfs(&grid, x, y - 1)
    }
}