Stock Profit Pairs

This repository contains a solution to the Profit Targets problem. The goal is to find the number of distinct pairs of stock profits that sum to a given target value. Each profit can only be used once, and pairs are considered unique regardless of order.

Problem Description

A financial analyst gathers all distinct pairs of stocks that reached a specific target profit. Given an array of stock profits and a target value, determine how many distinct pairs exist where the sum equals the target.

Example

Input:
stocksProfit = [6, 6, 3, 9, 3, 5, 1]
target = 12

Output:
2

Explanation:
There are 5 pairs where stocksProfit[i] + stocksProfit[j] = 12:
- (stocksProfit[0], stocksProfit[1]) = (6, 6)
- (stocksProfit[2], stocksProfit[3]) = (3, 9)
- (stocksProfit[3], stocksProfit[2]) = (9, 3)
- (stocksProfit[4], stocksProfit[3]) = (3, 9)
- (stocksProfit[1], stocksProfit[0]) = (6, 6)

After filtering duplicates, there are 2 unique pairs: (6, 6) and (3, 9).

Implementation

src/stockPairs.js

This function implements an optimized approach using two sets: one (seen) to track visited profits and another (used) to ensure profits are not reused across pairs. The algorithm runs in O(n) time complexity.

Function Logic

The function iterates through the stocksProfit array and checks if the complement of the current profit (i.e., target - profit1) exists in the seen set. If it does, and neither profit has been marked as used, the pair is counted, and both profits are added to the used set. The process ensures each profit is used only once per pair.

Code

function stockPairs(stocksProfit, target) {
  const seen = new Set();
  const used = new Set();
  let pairsCount = 0;

  stocksProfit.forEach((profit1) => {
    const profit2 = target - profit1;
    if (seen.has(profit2) && !used.has(profit1) && !used.has(profit2)) {
      pairsCount++;
      used.add(profit1);
      used.add(profit2);
    }
    seen.add(profit1);
  });
  
  return pairsCount;
}

Usage

Installation

Clone the repository and install dependencies:

git clone https://github.com/ricardoguerrasantana/stock-pairs.git
cd stock-pairs
npm install

Running the Code

Here’s how you can use the function:

const stockPairs = require('./src/stockPairs');

const stocksProfit = [6, 6, 3, 9, 3, 5, 1];
const target = 12;

console.log(stockPairs(stocksProfit, target)); // Output: 2

Running Tests

Run the test suite with Jest to validate the implementation:

npm test

Repository Structure

.
├── src/
│   ├── stockPairs.js
├── __tests__/
│   ├── stockPairs.test.js
├── package.json
├── README.md

License

This project is licensed under the MIT License. See the LICENSE file for details.