Arrays and prefix sums: count target-sum windows without rescanning every range

Arrays and prefix sums: Given an integer array nums and an integer target, return the number of contiguous, non-empty subarrays whose sum equals target.

Input: A JSON object { "nums": number[], "target": number }.

Output: A JSON integer equal to the number of matching contiguous subarrays.

Constraints:

0 <= nums.length <= 100000
nums may contain negative values and zero
The result fits in a safe JSON integer

Read one JSON value from stdin and print exactly one JSON-serialized answer to stdout with no extra text.

Difficulty: EASY. Variant: 4. Balance correctness, maintainability, and clear review-ready code.

Practice context

This coding (algo) exercise trains prompt interpretation, explicit assumptions, a concrete response, and a concise explanation of the decisions made. It is marked easy difficulty.

The signed-in workspace provides the tools required by the round, such

What this task practices

This coding (algo) exercise trains the same sequence expected in an interview: understand the prompt, make assumptions explicit, produce a concrete answer, and explain the decisions behind it. The task is marked easy difficulty. The private workspace adds the tools required by this round, such as recording, code execution, diagrams, evidence panels, or structured notes. It also preserves the attempt so later feedback can be compared with previous work. Evaluation is based on task-specific criteria and the candidate seniority selected in the preparation path. Public pages never expose the reference solution, hidden tests, evaluator instructions, or another candidate’s work.