Two Sum II - Input Array Is Sorted

📜 Problem Statement: Given a 1-indexed array of integers numbers that is already sorted in non-decreasing order, find two numbers such that they add up to a specific target number. Let these two numbers be numbers[index1] and numbers[index2] where 1 <= index1 < index2 <= numbers.length.

Return the indices of the two numbers, index1 and index2, added by one as an integer array [index1, index2] of length 2.

The tests are generated such that there is exactly one solution. You may not use the same element twice.

Your solution must use only constant extra space.

Examples

🔹 Example 1:

Input:

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

Output:

[1,2]

Explanation: The sum of 2 and 7 is 9. Therefore, index1 = 1, index2 = 2. We return [1, 2].

🔹 Example 2:

Input:

numbers = [2,3,4]
target = 6

Output:

[1,3]

Explanation: The sum of 2 and 4 is 6. Therefore index1 = 1, index2 = 3. We return [1, 3].

🔹 Example 3:

Input:

numbers = [-1,0]
target = -1

Output:

[1,2]

Explanation: The sum of -1 and 0 is -1. Therefore index1 = 1, index2 = 2. We return [1, 2].

📝 Constraints:

• 2 <= numbers.length <= 3 * 10^4

• -1000 <= numbers[i] <= 1000

• numbers is sorted in non-decreasing order.

• -1000 <= target <= 1000

• The tests are generated such that there is exactly one solution.