Two Sum II - Input Array Is Sorted — Medium Coding Interview Question

Given a 1-indexed array of integers numbers sorted in non-decreasing order, find two numbers such that they add up to target. Return the indices as [index1, index2] (1-indexed), where index1 < index2. You may not use the same element twice.

Example

Input: numbers = [2,7,11,15], target = 9

Output: [1,2]

Constraints

• 2 ≤ numbers.length ≤ 3 × 10⁴
• -1000 ≤ numbers[i] ≤ 1000
• numbers is sorted in non-decreasing order
• Exactly one valid answer exists

Topics & Companies

Topics: arrays, two-pointers

Asked by: Amazon, Google, Meta, Microsoft, Adobe

Optimal Solution Complexity

Time complexity: O(n). Space complexity: O(1).

Practice more

• All DSA Problems
• DSA Patterns