How should I practice Number of Ways to Reach a Position After Exactly K Steps?

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

Is Number of Ways to Reach a Position After Exactly K Steps associated with Bloomberg LP?

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

Number of Ways to Reach a Position After Exactly K Steps

Bloomberg LP● MediumNEW GRADPHONE SCREEN

Learn

Problem statement

You stand at integer position startPos. Each step moves exactly one unit left or right.

Return the number of distinct step sequences that reach endPos after exactly k steps, modulo 1,000,000,007.

Function

numberOfWays(startPos: int, endPos: int, k: int) → int

Examples

Example 1

startPos = 1endPos = 2k = 3return = 3

Exactly two right moves and one left move are needed, which can be ordered in three ways.

Example 2

startPos = 2endPos = 5k = 10return = 0

The distance and step count have different parity.

Constraints

-1000 <= startPos, endPos <= 1000.
0 <= k <= 1000.