Number of Islands - Leetcode 200 | DFS

Given an `m x n` 2D binary grid `grid` which represents a map of `'1'`s (land) and `'0'`s (water), return _the number of islands_.
An *island* is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water.
Problem: leetcode.com/p...
Code link: k5kc.com/cs/pr...