Add new binary search example using go

golang/1539.go

@@ -0,0 +1,39 @@
+package golang
+
+func binarySearch1539(arr []int, target int, size int) int {
+	left, right := 0, size - 1
+
+	for left <= right {
+		middle := (left + right) / 2
+
+		if arr[middle] == target {
+			return target
+		} else if target > arr[middle] {
+			left = middle + 1
+		} else if target < arr[middle] {
+			right = middle - 1
+		}
+	}
+
+	return -1
+}
+
+func findKthPositive(arr []int, k int) int {
+
+	count := 0
+	size := len(arr)
+
+	for i := 1; i <= arr[size - 1]; i++ {
+		result := binarySearch1539(arr, i, size)
+
+		if  result == -1 {
+			count++
+
+			if count == k {
+				return i
+			}
+		}
+	}
+
+	return arr[size - 1] + (k - count)
+}

golang/1539_test.go

@@ -0,0 +1,27 @@
+package golang
+
+import "testing"
+
+func TestFirstFindKthPositive(t *testing.T) {
+	arr := []int{2,3,4,7,11}
+	k := 5
+
+	result := findKthPositive(arr, k)
+	expected := 9
+
+	if result != expected {
+		t.Fatalf("findKthPositive(%v, %v) = %v but expected %v", arr, k, result, expected)
+	}
+}
+
+func TestSecondFindKthPositive(t *testing.T) {
+	arr := []int{1,2,3,4}
+	k := 2
+
+	result := findKthPositive(arr, k)
+	expected := 6
+
+	if result != expected {
+		t.Fatalf("findKthPositive(%v, %v) = %v but expected %v", arr, k, result, expected)
+	}
+}

golang/README.md

@@ -2,3 +2,4 @@
 | -------------- | ------------- | ------------------------------------------------------------------------------------ |
 | 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/ |
+| 1539.go        | Binary Search | https://leetcode.com/problems/kth-missing-positive-number/                           |