Climbing Stairs

Python data engineering interview problem. Difficulty: advanced. Pattern: Dynamic Programming. About 18 minutes. Part of the Pro drill bank.

Number of ways to climb n stairs taking 1 or 2 steps. Treat this as a production helper: match the contracted return shape, including empty and duplicate inputs.

A workflow has n steps, and each move can advance one or 2 steps. Count the different move sequences. Return the number of ways to reach exactly step n using only one-step and 2-step moves. Order matters, so 1 then 2 differs from 2 then 1. Write climb_stairs(n: int) -> int. For n = 3, the sequences are 1+1+1, 1+2 and 2+1, giving 3. The starter file already contains the function name, harness and print lines. Keep them and fill only the function body.

Requirements

• Count ordered sequences.
• Use only steps of size 1 or 2.
• Return an integer count.

Constraints

• n is a non-negative integer.
• There is one way to reach step 1 and one empty way to reach step 0.

Examples

Input: climb_stairs(3) Output: 3 Three sequences.

Topics: lakebench, python, dp, fibonacci.

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