flash on 2010-5-28

/**
 * Copyright uwi ( http://wonderfl.net/user/uwi )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/AsXz
 */

package {
	import flash.display.Sprite;
	import flash.text.TextField;
	import flash.utils.getTimer;
	// @see http://projecteuler.net/index.php?section=problems&id=
	public class Euler extends Sprite {
		private var _tf : TextField;
  
		public function Euler() {
			_tf = new TextField();
			_tf.width = 465;
			_tf.height = 465;
			addChild(_tf);
			
			var s : int = getTimer();
			tr(solve(2010));
			var g : int = getTimer();
			tr((g - s) + " ms");
		}

		private function solve(N : uint) : Number
		{
			var ret : Number = 0;
			for(var i : uint = 1;i < N;i++){
				ret += rec(i+1, i, i, N);
			}
			return ret;
		}
		
		private function rec(a : Number, b : Number, pos : uint, N : uint) : Number
		{ 
			var ret : Number = 0;
			for(var i : uint = pos;a * (i + 1) - b * i <= N;i++){
				if(a * (i + 1) - b * i == N){
					ret++;
				}else{
					ret += rec(a * (i + 1), b * i, i, N);
				}
			}
			return ret;
		}

		private function tr(...o : Array) : void
		{
			_tf.appendText(o + "\n");
			_tf.scrollV = _tf.maxScrollV;
		}
	}
}