lookandsay

/*
Implement LookAndSay function. For example, first, let user input a number, say 1. 
Then, the function will generate the next 10 numbers which satisfy this condition: 
1, 11,21,1211,111221,312211... 
explanation: first number 1, second number is one 1, so 11. Third number is two 1(previous number), 
so 21. next number one 2 one 1, so 1211 and so on...
*/

private static LinkedList<String> lookandsay(int i){
  //int num = i;
	String num = new String();
	num = String.valueOf(i);

	LinkedList<String> list = new LinkedList<String>();
	
	
	for (int iter=1; iter<10; iter++){
		/*this version can also work, but the number grows rapidly, and will exceed the limit of Integer
		if (num == 0) stack.push(num);
		else {
			while( num != 0){
				int tmp = num % 10;
				stack.push(tmp);
				num = num / 10;
			}
		}
		 */

		for(int ind=num.length(); ind>0; ind--){
			stack.push(Character.getNumericValue(num.charAt(ind-1)));
		}
		
		int current = stack.pop();
		int count = 1;
		String result = new String();
		int next;
		while (!stack.empty()){
			next = stack.peek();
			if (next == current){
				count++;
				current = next;
				stack.pop();
			} else {
				result = result + count;
				result = result + current;
				current = stack.pop();
				count = 1;
				}
		}
		result = result + count;
		result = result + current;
		//num = Integer.parseInt(result);
		num = result;
		System.out.println(num);
		list.add(result);
	
	}
	System.out.println();
	return list;
}

private static Stack<Integer> stack = new Stack<Integer>();