How should I practice Count Pairs with K Divisible Values in the Interval?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Chubb online assessment problems in FastPrep.

Is Count Pairs with K Divisible Values in the Interval associated with Chubb?

FastPrep tags this as a Chubb online assessment coding practice problem when the problem catalog has that company and stage context.

Count Pairs with K Divisible Values in the Interval

Chubb● HardNEW GRADOA

Learn

Problem statement

Given an integer array arr, a nonnegative integer k, and a positive integer x, count index pairs (i, j) with i < j and arr[i] <= arr[j] such that the inclusive integer interval [arr[i], arr[j]] contains exactly k multiples of x.

Pairs are counted by index, so equal values at different positions are distinct. Zero is divisible by every positive x. Return the number of valid pairs.

Function

countValidPairs(arr: int[], k: int, x: int) → long

Examples

Example 1

arr = [1,2,3,4,5]k = 2x = 2return = 4

The valid pairs have value intervals [1,4], [1,5], [2,4], and [2,5], each containing the multiples 2 and 4.

Example 2

arr = [-3,0,2]k = 2x = 3return = 2

The intervals [-3,0] and [-3,2] each contain -3 and 0. The interval [0,2] contains only 0.

Constraints

1 <= arr.length <= 200000.
-1000000 <= arr[i] <= 1000000.
0 <= k <= 2000000.
1 <= x <= 1000000.
The answer fits in a signed 64-bit integer.