leetcode medium - Number of Islands

 Leetcode

https://leetcode.com/problems/number-of-islands/

https://www.youtube.com/watch?v=U6-X_QOwPcs&list=PLU_sdQYzUj2keVENTP0a5rdykRSgg9Wp-

Code

class Solution {

    public int numIslands(char[][] grid) {

        int count = 0;

        for (int i = 0; i < grid.length; i++) {

            for (int j = 0; j < grid[i].length; j++) {

                if (grid[i][j] == '1') {

                    count++;

                    clearIsland(grid, i, j);

                }

            }

        }

        return count;

    }

    private void clearIsland(char[][] grid, int i, int j) {

        if (i < 0 || j < 0 || i >= grid.length || j >= grid[i].length || grid[i][j] == '0') return;

        grid[i][j] = '0';

        clearIsland(grid, i, j-1); // up

        clearIsland(grid, i, j+1); // down

        clearIsland(grid, i-1, j); // left

        clearIsland(grid, i+1, j); // right

    }

}