Two Pointers/Two Sum II - Input Array Is SortedMedium

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Two Sum II - Input Array Is Sorted

Two Pointers·Medium

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.

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

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

Output: [1,2]

numbers[0] + numbers[1] = 2 + 7 = 9. Return 1-indexed [1,2].

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

Output: [1,3]

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

Output: [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.

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Tests

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Passed32 ms

First attempt — retry to track metric movement here.

Your approach

Pattern:Two Pointers
Time:O(N)
Space:O(1)

Complete approach — pattern and complexity both named.

Coach

What you got right

You correctly matched the sorted input requirement and implemented a linear-time scan using two pointers.

Where it diverged

No divergence detected. The code correctly aligns with the stated approach.

Next attempt: focus on

Try solving related sliding window problems to build familiarity with two-pointer variants.

Signals

No signals fired — clean run, you stayed in flow.