Depth First Search

dfs.py

# Leetcode 200
# https://leetcode.com/problems/number-of-islands/
def dfs(grid, i, j):
    if grid[i][j] == "1":
        grid[i][j] = "0"
        if i-1 >= 0:
            dfs(grid, i-1, j)
        if i+1 < len(grid):
            dfs(grid, i+1, j)
        if j-1 >= 0:
            dfs(grid, i, j-1)
        if j+1 < len(grid[0]):
            dfs(grid, i, j+1)