number-of-islands.js

number-of-islands.js

/**
 * Created by Hoan Nguyen on 11/9/2017.
 */


/**
 * @param {character[][]} grid
 * @return {number}
 */

var n;
var m;

var numIslands = function(grid) {
	var count = 0;
	n = grid.length;
	if (n == 0) return 0;
	m = grid[0].length;

	for (var i = 0; i < n; i++) {
		for (var j = 0; j < m; j++)
			if (grid[i][j] == '1') {
				DFS(grid, i, j);
				++count;
			}
	}
	return count;
};

function DFS(grid, i, j) {
	if (i < 0 || j < 0 || i >= n || j >= m || grid[i][j] != '1') return;
	grid[i][j] = '0';
	DFS(grid, i + 1, j);
	DFS(grid, i - 1, j);
	DFS(grid, i, j + 1);
	DFS(grid, i, j - 1);
}