1、题目:
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.
Example 1:
Input: 2 Output: 2 Explanation: There are two ways to climb to the top. 1. 1 step + 1 step 2. 2 steps
Example 2:
Input: 3 Output: 3 Explanation: There are three ways to climb to the top. 1. 1 step + 1 step + 1 step 2. 1 step + 2 steps 3. 2 steps + 1 step
2、解答: 假设第n步,你可以由n-1步,走1步到达第n步,n-2,走2步到达第n步。
3、代码:
C++代码
class Solution { public: int climbStairs(int n) { vector<int> f(n+1,0); f[0] = 1; f[1] = 1; for(int i=2;i<=n;i++) f[i] = f[i-1] +f[i-2]; return f[n]; } };
python代码
class Solution: def climbStairs(self, n): """ :type n: int :rtype: int """ if n < 1: return 0 f = [1 for i in range(n+1)] for i in range(2,len(f)): f[i] = f[i-1] + f[i-2] return f[n]