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?
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这个题面试题还是比较常见的
讨论的帖子：
原理：
This problem is a Fibonacci problem. F(n)=F(n-1)+F(n-2); Solving this problem by recursion ,we will do a lot of same recursion. Example: F(10)=F(9)+F(8); F(9)=F(8)+F(7); we calculate F(8) twice,when n is large,this will increase as a rate of n's exponent.
So a more efficient way to solve this problem is from Bottom to Top. Calculate F(0) ,F(1); then F(2).........
人生ac最快的代码：
class Solution {
public:
int climbStairs(int n)
{
int stepone = 0;
int steptwo = 1;
int sum = 0;
for(int i = 0;i<n;i++)
{
sum = stepone + steptwo;
stepone = steptwo;
steptwo = sum;
}
return sum;
}
};
DP算法求解：
简洁的代码：
递归：
python：
