剑指 Offer 10- II. 青蛙跳台阶问题

class Solution {
public:
    int numWays(int n) {
        int a=1, b=1, sum=2;
        if(n==0||n==1) return 1;
        for(int i=1;i 
Python 
class Solution:
    def numWays(self, n: int) -> int:
        a, b = 1, 1
        if n<=1: return 1
        for _ in range(n):
            a, b = b, a+b
        return a%1000000007