Climbing Stairs

LeetCode: https://leetcode.com/problems/climbing-stairs/

You are climbing a staircase. It takes n steps to reach the top. Each time you can climb either 1 or 2 steps. Return how many distinct ways you can climb to the top.

1def climbStairs(n: int) -> int:
2    if n <= 2:
3        return n
4    a, b = 1, 2
5    for _ in range(3, n + 1):
6        a, b = b, a + b
7    return b

House Robber

n=5

a=1

b=2

Step 1 / 5

Step 1:

Use dp[n]=dp[n-1]+dp[n-2]. For n=5, initialize a=dp[1]=1 and b=dp[2]=2.

Pointers: i=2

Focus: select @ [0, 1]

n=5a=1b=2