Sorted Pair Sum

Problem Description

Given a sorted array of integers in non-decreasing order and a target sum, your task is to find a pair of numbers in the array that adds up exactly to the target value. The solution must use the two-pointer technique to achieve an O(n) time complexity and O(1) extra space.

If such a pair exists, return the indices (0-indexed) of the two numbers. If there are multiple valid pairs, return any one of them. If no such pair exists, return [-1, -1].

Example

Given the array: [1, 2, 3, 4, 6] and target sum: 8, the pair (2, 6) (indices [1, 4]) adds up to 8.

Additional Context

Today is Pi Day (March 14), a perfect day to celebrate circles, but also a good day to make your algorithms round the corner with efficient techniques like the two-pointer method!

Function Signature

Define a function that takes in a sorted array and a target integer, and returns an array of two integers representing the indices of the pair that sums up to the target.