爬一個階梯。到頂端總共需走n階,每次你都可以選擇爬1階或2階,問有幾種不同的方法可以爬到階梯頂端?
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.