Leetcode 1: Two Sum Problem - A Leetcode Classic in Swift

*Explanation: Two Sum Problem*

*Problem:*
Given an array of integers `nums` and an integer `target`, find two numbers such that they add up to `target`.

*Solution Approach: Using a Hash Map*

1. *Create an Empty Hash Map:*
- Initialize an empty hash map `dict` to store numbers and their corresponding indices.

2. *Iterate Through the Array:*
- For each number `num` and its index `index` in the array:
- Check if the complement `target - num` exists in the hash map.
- If it does, return the indices of the complement and the current number.
- Otherwise, add the current number and its index to the hash map.

3. *Return an Empty Array:*
- If no pair is found after iterating through the entire array, return an empty array.

*Time and Space Complexity:*

- *Time Complexity:* O(n), where n is the number of elements in the array. We iterate through the array once.
- *Space Complexity:* O(n), in the worst case, when all elements are unique and stored in the hash map.

*Key Points:*

- The hash map allows for efficient lookup of complements.
- This approach avoids nested loops, resulting in a linear time complexity.
- The hash map stores the number and its index, enabling quick retrieval of the corresponding index.

By leveraging the properties of a hash map, we can efficiently solve the Two Sum problem.

#leetcodeswift
#leetcode
#leetcodesolution
#100daysofcode
#datastructures
#datastructuresandalgorithms
#swift
#swiftprogramming