In the Java method to find two candidates in an array that sum up to a target, what does the sorting step accomplish?

• A. It makes the array elements unique
• B. It allows for efficient searching of pairs
• C. It converts the array into a binary tree
• D. It groups negative and positive numbers together

Answer: (B)

The sorting step in the Java method to find two candidates in an array that sum to a target is crucial because it allows for efficient searching of pairs. When the array is sorted, it becomes easier to identify pairs of numbers that can potentially meet the target sum. For example, after sorting, you can utilize techniques like the two-pointer technique, where one pointer starts at the beginning of the array and the other at the end. By moving these pointers based on whether their sum is less than or greater than the target, you can quickly find the desired pair or determine that no such pair exists.

This method significantly reduces the time complexity compared to a brute-force approach, where you would have to check every possible pair of numbers. The sorted order provides a structured way to navigate through the array, leading to a more efficient solution.

The other options do not accurately represent the purpose of sorting in this context. Sorting does not make elements unique (as duplicates can still exist), nor does it convert the array into a binary tree or group negative and positive numbers together in a way that is directly relevant to finding the sum. Hence, the primary role of sorting in this method is to facilitate efficient pair searching.