Sorted Array Pair Search

Medium

You are provided with a 1-indexed integer array numbers that is pre-arranged in ascending order (non-decreasing). Your objective is to identify two distinct elements within this array that, when summed together, equal a specified target value. Formally, you must find positions first and second such that 1 \leq first < second \leq numbers.length and numbers[first] + numbers[second] = target . Return an array containing these two 1-based indices [first, second] . Key Constraints: The input is guaranteed to have exactly one valid solution . You cannot use the same element twice (i.e., you must select two distinct positions). Your algorithm must use constant (O(1)) additional space — leveraging the sorted property of the input is essential. This problem tests your ability to exploit the inherent ordering of data to achieve optimal space efficiency while maintaining excellent time performance.

Input

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

Output

[1, 2]

Explanation

The values at positions 1 and 2 are 2 and 7 respectively. Their sum is 2 + 7 = 9, which matches the target. Hence, we return [1, 2].

Input

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

Output

[1, 3]

Explanation

The element at position 1 is 2, and the element at position 3 is 4. Since 2 + 4 = 6 equals the target, we return [1, 3].

Input

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

Output

[1, 2]

Explanation

The array contains -1 at position 1 and 0 at position 2. Adding them yields -1 + 0 = -1, matching the target value.

Constraints