Climbing Stairs

You are climbing a stair case. It takes n steps to reach to the top.

Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?

Note: Given n will be a positive integer.

Solution:

public int climbStairs(int n) { if (n == 0 || n == 1 || n == 2) { return n; } int one_step_before = 2; int two_steps_before = 1; int all_ways = 0; for (int i = 2; i < n; i++) { all_ways = one_step_before + two_steps_before; two_steps_before = one_step_before; one_step_before = all_ways; } return all_ways; }