Sorted Array Pair Search

MEDIUM20 pts

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 ≤ first < second ≤ 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.

Example

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].

Example

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].

Example

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.

Accepted0/0·0% Acceptance

Constraints

2 ≤ numbers.length ≤ 3 × 10⁴
-1000 ≤ numbers[i] ≤ 1000
numbers is arranged in non-decreasing (ascending) order
-1000 ≤ target ≤ 1000
Exactly one valid pair exists for every input

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target =

numbers =

[2,7,11,15]

Formally, you must find positions first and second such that 1 ≤ first < second ≤ 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.

Sorted Array Pair Search

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Sorted Array Pair Search

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