🧮#02 Algorithm Guidance: Two Sum

📝 Introduction

This guidance explains how to find two numbers in an array that add up to a specific target value. It provides step-by-step instructions, sample code snippets, and real-world project examples.

⚙️ Algorithm Overview

The "Two Sum" algorithm aims to find two numbers in an array whose sum equals a given target value. The algorithm returns the indices of these two numbers.

Algorithm Steps

1. Create a Map: Initialize an empty map to store the indices of array elements.

2. Iterate Through Array:

   • Iterate through the array elements.

   • For each element, calculate its complement (target - current element).

   • Check if the complement exists in the map.

   • If found, return the indices of the current element and its complement.

   • If not found, add the current element and its index to the map.

3. Handle Edge Cases: If no such pair is found, return an empty list.

Dart Implementation

class Solution {
  List<int> twoSum(List<int> nums, int target) {
    Map<int, int> numMap = {};

    for (int i = 0; i < nums.length; i++) {
      int complement = target - nums[i];
      if (numMap.containsKey(complement)) {
        return [numMap[complement], i];
      }
      numMap[nums[i]] = i;
    }

    return [];
  }
}

Example Scenarios

1. Online Shopping Platform - Cart Total Calculation

Dart Code:

void main() {
  Solution solution = Solution();
  List<int> nums = [10, 20, 30, 40];
  int target = 50;
  List<int> result = solution.twoSum(nums, target);
  print(result); // Output: [0, 2] (Indices of 10 and 30)
}

In an online shopping platform, the "Two Sum" algorithm can be used to find two items in the cart whose combined prices match a user's specified budget. This helps users manage their expenses and make informed purchasing decisions.

2. Inventory Management System - Product Bundling

Dart Code:

void main() {
  Solution solution = Solution();
  List<int> nums = [15, 25, 35, 45];
  int target = 60;
  List<int> result = solution.twoSum(nums, target);
  print(result); // Output: [0, 3] (Indices of 15 and 45)
}

In an inventory management system, the "Two Sum" algorithm can assist in identifying two products whose combined quantities meet a retailer's stocking requirements. This feature helps streamline inventory replenishment processes and optimize stock levels.

3. Ride-Sharing Application - Fare Calculation

Dart Code:

void main() {
  Solution solution = Solution();
  List<int> nums = [5, 10, 15, 20];
  int target = 25;
  List<int> result = solution.twoSum(nums, target);
  print(result); // Output: [1, 2] (Indices of 10 and 15)
}

In a ride-sharing application, the "Two Sum" algorithm can be applied to identify two ride options whose fares sum up to a user's specified budget. This functionality enables users to select the most cost-effective transportation options for their trips.

🎉 Conclusion

This guidance provided a step-by-step explanation of the "Two Sum" algorithm, accompanied by real-world project examples demonstrating its practical applications in various industries. The algorithm's versatility makes it valuable for solving a wide range of problems in software development.

📚 References

• Dart Programming Language Documentation: Dart.dev
• Dart Language Tour: Dart Language Tour
• Dart API Reference: Dart API Reference

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This guidance provides software developers with the step-by-step process of implementing the "Two Sum" algorithm, supported by real-world project examples and comprehensive explanations.