Solve problem '167) two sum ii - input array is sorted'

Author: ozantopal

problems/167-two-sum-ii-input-array-is-sorted/README.md

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+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.
+
+**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**.

problems/167-two-sum-ii-input-array-is-sorted/main.go

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+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println(twoSum([]int{2, 7, 11, 15}, 9))
+	fmt.Println(twoSum([]int{2, 3, 4}, 6))
+	fmt.Println(twoSum([]int{-1, 0}, -1))
+}
+
+func twoSum(numbers []int, target int) []int {
+	i, j := 0, len(numbers)-1
+	for i < j {
+		if numbers[i]+numbers[j] == target {
+			return []int{i + 1, j + 1}
+		} else if numbers[i]+numbers[j] < target {
+			i++
+		} else {
+			j--
+		}
+	}
+
+	return nil
+}