Two Sum Pseudo Code

Problem Statement

Given an array of integers and an integer target, return the indices of the two numbers such that they add up to the target.

Inputs

• An array of integers: nums
• An integer: target

Outputs

• An array of two integers representing the indices of the two numbers that add up to target.

Assumptions

• Each input would have exactly one solution.
• The same element may not be used twice.

Pseudo Code

1. Function Definition Define a function twoSum(nums, target).

2. Initialize a Dictionary Create an empty dictionary num_map to store the numbers and their corresponding indices.

3. Iterate Over the Array For each index i from 0 to the length of nums - 1:

   • Set complement to target - nums[i].

4. Check for the Complement

   • If complement exists in num_map:
     • Return [num_map[complement], i] // Indices of the two numbers.

5. Store the Current Number

   • Otherwise, add nums[i] to num_map with the value as index i.

6. Handle No Solution Found If no two numbers sum to the target, return an indication (like [-1, -1]).

Complete Pseudo Code

function twoSum(nums, target):
    create an empty dictionary num_map

    for i from 0 to length of nums - 1:
        set complement to target - nums[i]
        
        if complement in num_map:
            return [num_map[complement], i]

        num_map[nums[i]] = i

    return [-1, -1]  // In case no solution is found

Conclusion

The pseudo code provides a clear and straightforward implementation to solve the Two Sum problem using a hash map for efficient lookups. This approach offers a time complexity of O(n) and space complexity of O(n), making it optimal for this problem.