DSA-Java/LC_200 at main · shreyasingh260/DSA-Java · GitHub

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class Solution {

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

        int count = 0;

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

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

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

                    count++;

                    dfs(grid, i, j);
                }
            }
        }

        return count;
    }

    private void dfs(char[][] grid, int row, int col) {

        if (row < 0 ||
            row >= grid.length ||
            col < 0 ||
            col >= grid[0].length ||
            grid[row][col] == '0') {

            return;
        }

        grid[row][col] = '0';

        dfs(grid, row + 1, col);

        dfs(grid, row - 1, col);

        dfs(grid, row, col + 1);

        dfs(grid, row, col - 1);
    }
}