Climbing Stairs Leetcode


#1

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

The below code uses DP to calculate number of steps at current i where i could be 1 to n by adding the last 2 values.

func climbStairs(n int) int {
    if n<1{return 1}
    dp := make([]int, n+1)
    dp[0]=1
    dp[1]=1
    for i:=2;i<=n;i++{
        dp[i]=dp[i-1]+dp[i-2]
    }
    return dp[n]
}