剑指 Offer 10- II. 青蛙跳台阶问题

原题链接：剑指 Offer 10- II. 青蛙跳台阶问题

 

solution:

class Solution {
public:
    int numWays(int n) {
        if(n <= 1) return 1;
        vector<int> dp(n + 1);
        dp[0] = 1;
        dp[1] = 1;
        for(int i = 2;i <= n;i++) {
            dp[i] = (dp[i - 1] + dp[i -2]) % 1000000007;
        }
        return dp[n];
    }
};