leetcode70- Climbing Stairs
难度：eazy
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.
思路—木有思路，借鉴别人的。
当台阶数输入为1, 2, 3, 4, 5, 6, 7, 8, 9, 10时，输出为1, 2, 3, 5, 8, 13, 21, 34, 55, 89，是斐波那契数列！除了1和2以外，其余均为前两个数相加
python 交换两个变量的值