How should I practice Count Staircase Ways?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Goldman Sachs phone screen problems in FastPrep.

Is Count Staircase Ways associated with Goldman Sachs?

FastPrep tags this as a Goldman Sachs phone screen coding practice problem when the problem catalog has that company and stage context.

Problem · Dynamic Programming

Count Staircase Ways

Learn this problem

● Easy

Goldman SachsFULLTIMEPHONE SCREEN

Problem statement

A staircase has n steps. Starting before the first step, each move climbs exactly one or two steps.

Return the number of distinct ordered move sequences that land exactly on step n. For n = 0, return 1 for the empty sequence.

Function

countStaircaseWays(n: int) → long

Examples

Example 1

n = 4return = 5

The valid step sequences are 1111, 112, 121, 211, and 22.

Example 2

n = 0return = 1

The empty climb is one valid way.

Constraints

0 <= n <= 90
The answer fits in a signed 64-bit integer.