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$ curl repovive.com/roadmaps/math-fundamentals/counting-principles/climbing-stairs-implementation

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$ curl repovive.com/roadmaps/math-fundamentals/counting-principles/climbing-stairs-implementation

Repovive

Climbing Stairs - Implementation - Counting Principles | Math Fundamentals | Repovive

Repovive.

Math Fundamentals18 sections · 842 units13h total

Open in Course

Climbing Stairs - Implementation

The pseudocode

Here is the full solution:


function climbStairs(n)
    if n <= 2 then
        return n
    prev2 := 1
    prev1 := 2
    for i from 3 to n
        current := prev1 + prev2
        prev2 := prev1
        prev1 := current
    return prev1

Time: $O(n)$ . Space: $O(1)$ . This is the space-optimized version since you only need the last two values.