Add new binary search example using go

golang/1608.go

@@ -0,0 +1,33 @@
+package golang
+
+import "sort"
+
+// binarySearch looks for the first element equal of immediate greater than target
+func binarySearch(nums []int, target int) int {
+	left, right := 0, len(nums)-1
+
+	for left <= right {
+		middle := (left + right) / 2
+
+		if nums[middle] >= target {
+			right = middle - 1
+		} else {
+			left = middle + 1
+		}
+	}
+
+	return len(nums) - left
+}
+
+func specialArray(nums []int) int {
+
+	sort.Ints(nums)
+
+	for i := 1; i <= len(nums); i++ {
+		if binarySearch(nums, i) == i {
+			return i
+		}
+	}
+
+	return -1
+}

golang/1608_test.go

@@ -0,0 +1,43 @@
+package golang
+
+import "testing"
+
+func TestSpecialArray(t *testing.T) {
+	nums := []int{3, 5, 1}
+	expected := 2
+	result := specialArray(nums)
+
+	if result != expected {
+		t.Fatalf(`specialArray(%#v) = %v != %v`, nums, result, expected)
+	}
+}
+
+func TestSecondSpecialArray(t *testing.T) {
+	nums := []int{1, 4, 5}
+	expected := 2
+	result := specialArray(nums)
+
+	if result != expected {
+		t.Fatalf(`specialArray(%#v) = %v != %v`, nums, result, expected)
+	}
+}
+
+func TestThirdSpecialArray(t *testing.T) {
+	nums := []int{0, 1}
+	expected := 1
+	result := specialArray(nums)
+
+	if result != expected {
+		t.Fatalf(`specialArray(%#v) = %v != %v`, nums, result, expected)
+	}
+}
+
+func TestFourthSpecialArray(t *testing.T) {
+	nums := []int{0, 0}
+	expected := -1
+	result := specialArray(nums)
+
+	if result != expected {
+		t.Fatalf(`specialArray(%#v) = %v != %v`, nums, result, expected)
+	}
+}

golang/README.md

@@ -1,3 +1,4 @@
-| Problem Number | Tag        | URL                                           |
-| -------------- | ---------- | --------------------------------------------- |
-| 888.go         | Hash table | https://leetcode.com/problems/fair-candy-swap |
+| Problem Number | Tag           | URL                                                                                  |
+| -------------- | ------------- | ------------------------------------------------------------------------------------ |
+| 888.go         | Hash table    | https://leetcode.com/problems/fair-candy-swap                                        |
+| 1608.go        | Binary Search | https://leetcode.com/problems/special-array-with-x-elements-greater-than-or-equal-x/ |