Learn how to solve the Leetcode problem of id 1, whose title is Two Sum, using the Java programming language.

https://leetcode.com/problems/two-sum

The Data Structures and Algorithms (DSA) lesson uses a hash map approach to solve the problem.

Mathematically, the sum of a and b resulting in target can be expressed as one number being the target minus the other number.

So we can solve the problem by iterating over the integers and computing the difference between the target and the current number.

If the difference is a number that we have seen before, as recorded in a hash map, then we return the indices of the number seen before and the current index.

Otherwise, record that the current number was seen by placing a key-value pair of the number and its index in the array, respectively.

The time complexity for the solution is O(n) and its space complexity is O(n).

DSA problems are sometimes asked during tech job interviews for positions such as Software Engineer, so you can use the challenge to practice that skill.