Pairs Below the Limit

Easy

A sensor produced a series of readings readings — integers that may be negative. An engineer wants to know which two readings together stay under the threshold limit. Return the number of index pairs i < j where readings[i] + readings[j] is strictly less than limit.

Example 1

readings=[3, -2, 0, 4], limit=2 → 2

The pairs 3 + (−2) = 1 and (−2) + 0 = −2 qualify; (−2) + 4 = 2 does not, since 2 is not below 2. That makes two pairs.

Example 2

readings=[1, 1, 1], limit=3 → 3

Any two readings sum to 2 < 3, and there are three pairs.

Example 3

readings=[-5, 10], limit=-10 → 0

The only pair sums to 5, which is not below −10.

Constraints

1 ≤ len(readings) ≤ 50
−100 ≤ readings[i] ≤ 100
−200 ≤ limit ≤ 200

Have you seen this problem in a real interview?

Solved by0

Tried by0

Submissions0

Acceptance—

Topics

Array Two Pointers Binary Search Sorting

Similar problems

Values in Both Lists Easy Shared Values With Repeats Easy Best Pair Under the Limit Easy Twice as Much Easy Far From Every Mark Easy

Input

readings=[3, -2, 0, 4], limit=2

Expected

Run checks the first 3 tests in your browser. Submit checks all 111 tests on the server, hidden ones included.