Climbing Stairs - Leetcode

Iterrative 实现递归

public class Solution {public int climbStairs(int n) {int prev=0, cur=1;for(int i=1; i<=n; i++){int tmp=cur;cur += prev;prev=tmp;}return cur;}
}

public class Solution {public int climbStairs(int n) {int[] f=new int[n+1];int[] fun=new int[n+1];for(int i=0; i<=n; i++){f[i]=i;}for(int i=3; i<=n; i++){f[i]=f[i-1]+f[i-2];}return f[n];}
}

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?