Challenge 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 <= len(numbers).
- 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.
- This challenge corresponds to LeetCode #167.
Constraints
2 <= len(numbers) <= 3 * 104-1000 <= numbers[i] <= 1000- numbers is sorted in non-decreasing order.
-1000 <= target <= 1000- The tests are generated such that there is exactly one solution.
- s consists only of printable ASCII characters.
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].
Solution
Below is my solution and some test cases. This solution has a linear time complexity O(n) and a constant space complexity O(1), where n is the length of the input list.
