Pair Count

L2 Easy Arrays & Hashing

Concept

Nested loops visit every ordered pair once. This brute-force approach is the baseline that clever hash-based solutions later improve on.

Count every pair of indices (i, j) with i < j where nums[i] + nums[j] equals target. Different index pairs count separately.

Examples

▸ nums = [1, 2, 3, 4, 5], target = 6

→ 2

▸ nums = [1, 1, 1], target = 2

→ 3

▸ nums = [], target = 5

→ 0

Progressive Hints

Hint 1 · Nudge

You have to consider every possible pairing exactly once.

Hint 2 · Plan

Use two nested loops so every pair of indexes (i, j) with i before j is visited exactly once. Bump a counter whenever the two values add up to target, and return the counter.

Hint 3 · Approach

count = 0. For i from 0 to the end: for j from i + 1 to the end: if nums[i] + nums[j] == target then count = count + 1. Return count.

Output

// Run your code to see the output here.