Add solution #1539

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,353 LeetCode solutions in JavaScript
+# 1,354 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1175,6 +1175,7 @@
 1535|[Find the Winner of an Array Game](./solutions/1535-find-the-winner-of-an-array-game.js)|Medium|
 1536|[Minimum Swaps to Arrange a Binary Grid](./solutions/1536-minimum-swaps-to-arrange-a-binary-grid.js)|Medium|
 1537|[Get the Maximum Score](./solutions/1537-get-the-maximum-score.js)|Hard|
+1539|[Kth Missing Positive Number](./solutions/1539-kth-missing-positive-number.js)|Easy|
 1550|[Three Consecutive Odds](./solutions/1550-three-consecutive-odds.js)|Easy|
 1551|[Minimum Operations to Make Array Equal](./solutions/1551-minimum-operations-to-make-array-equal.js)|Medium|
 1566|[Detect Pattern of Length M Repeated K or More Times](./solutions/1566-detect-pattern-of-length-m-repeated-k-or-more-times.js)|Easy|

solutions/1539-kth-missing-positive-number.js

@@ -0,0 +1,32 @@
+/**
+ * 1539. Kth Missing Positive Number
+ * https://leetcode.com/problems/kth-missing-positive-number/
+ * Difficulty: Easy
+ *
+ * Given an array arr of positive integers sorted in a strictly increasing order, and an integer k.
+ *
+ * Return the kth positive integer that is missing from this array.
+ */
+
+/**
+ * @param {number[]} arr
+ * @param {number} k
+ * @return {number}
+ */
+var findKthPositive = function(arr, k) {
+  let left = 0;
+  let right = arr.length - 1;
+
+  while (left <= right) {
+    const mid = Math.floor((left + right) / 2);
+    const count = arr[mid] - mid - 1;
+
+    if (count < k) {
+      left = mid + 1;
+    } else {
+      right = mid - 1;
+    }
+  }
+
+  return left + k;
+};