devdating.net Solution

From http://devdating.net/

Rocks are falling from the sky! You get an array of columns: rocks o and platforms #
Simulate rocks’ flight until they hit a platform, another rock or the bottom. Platforms stay put.
map is an array in the format ['ooo###...', ...] where map[2][5] translates to the rock at x: 2, y: 5
return the result after all rocks have stopped moving.

	(function() {
	var rows = map[0].length;
	var cols = map.length;
	String.prototype.replaceAt=function(index, character)
	{
	return this.substr(0, index) + character + this.substr(index+character.length);
	}
	var dropRocks = function(c)
	{
	for(var r = rows-1; r >= 0; r--)
	{
	if(map[c][r] == 'o' && map[c][r+1] == '.')
	{
	map[c] = map[c].replaceAt(r, '.');
	map[c] = map[c].replaceAt(r+1, 'o');
	r = rows-1;
	}
	}
	}
	var i = 0;
	for(i = 0; i < cols; i++)
	{
	dropRocks(i);
	}
	console.dir(map);
	return map;
	})();

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