Find the number of different ways to climb an n-stair staircase if each step is either one or two stairs.

Write a recursive algorithm in psuedocode as well as in Java for climbing n steps, one or two steps at a time and a non recursive algorithm as well.

Theory example: For a 3-stair staircase, it can be climbed in three ways: 1-1-1, 1-2, and 2-1.