Add two sum 2

Author: Gituser143

Easy/two-sum-ii-input-array-is-sorted.md

@@ -0,0 +1,41 @@
+Code
+====
+
+```go
+func twoSum(numbers []int, target int) []int {
+
+	nums := numbers
+
+	lb := 0
+	ub := len(nums) - 1
+
+	for ub > lb {
+		sum := nums[ub] + nums[lb]
+
+		if sum == target {
+			return []int{lb + 1, ub + 1}
+		} else if sum < target {
+			for lb < ub && nums[lb+1] == nums[lb] {
+				lb++
+			}
+			lb++
+		} else {
+			for lb < ub && nums[ub] == nums[ub-1] {
+				ub--
+			}
+			ub--
+		}
+	}
+
+	return []int{0, 0}
+}
+```
+
+Solution in mind
+================
+
+-	Since the array i sorted, we make use of two pointers, upper bound (ub) and lower bound (lb).
+
+-	We initialise ub, lb to `len(nums)-1` and 0 respectively. We check if the sum of elements at these indices are equal to target. If yes, we return indices.
+
+-	If the sum is lesser, we move the lower bound pointer higher up. If greater, we bring the upper bound pointer down.

README.md

@@ -5,7 +5,7 @@ My collection of leet code problems solved in GoLang!
 
 | [Easy](#easy) | [Medium](#medium) | [Hard](#hard) |
 |---------------|-------------------|---------------|
-| 22            | 37                | 8             |
+| 23            | 37                | 8             |
 
 Problems finished
 =================
@@ -57,6 +57,8 @@ Easy
 
 -	[range-sum-of-bst](Easy/range-sum-of-bst.md)
 
+-	[two-sum-ii-input-array-is-sorted](Easy/two-sum-ii-input-array-is-sorted.md)
+
 Medium
 ------