Add solution #1608

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,416 LeetCode solutions in JavaScript
+# 1,417 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1240,6 +1240,7 @@
 1603|[Design Parking System](./solutions/1603-design-parking-system.js)|Easy|
 1604|[Alert Using Same Key-Card Three or More Times in a One Hour Period](./solutions/1604-alert-using-same-key-card-three-or-more-times-in-a-one-hour-period.js)|Medium|
 1605|[Find Valid Matrix Given Row and Column Sums](./solutions/1605-find-valid-matrix-given-row-and-column-sums.js)|Medium|
+1608|[Special Array With X Elements Greater Than or Equal X](./solutions/1608-special-array-with-x-elements-greater-than-or-equal-x.js)|Easy|
 1657|[Determine if Two Strings Are Close](./solutions/1657-determine-if-two-strings-are-close.js)|Medium|
 1668|[Maximum Repeating Substring](./solutions/1668-maximum-repeating-substring.js)|Easy|
 1669|[Merge In Between Linked Lists](./solutions/1669-merge-in-between-linked-lists.js)|Medium|

solutions/1608-special-array-with-x-elements-greater-than-or-equal-x.js

@@ -0,0 +1,39 @@
+/**
+ * 1608. Special Array With X Elements Greater Than or Equal X
+ * https://leetcode.com/problems/special-array-with-x-elements-greater-than-or-equal-x/
+ * Difficulty: Easy
+ *
+ * You are given an array nums of non-negative integers. nums is considered special if there exists
+ * a number x such that there are exactly x numbers in nums that are greater than or equal to x.
+ *
+ * Notice that x does not have to be an element in nums.
+ *
+ * Return x if the array is special, otherwise, return -1. It can be proven that if nums is special,
+ * the value for x is unique.
+ */
+
+/**
+ * @param {number[]} nums
+ * @param {number} start
+ * @param {number} end
+ * @return {number}
+ */
+function specialArray(numbers) {
+  numbers.sort((a, b) => b - a);
+  let left = 0;
+  let right = numbers.length;
+
+  while (left <= right) {
+    const mid = Math.floor((left + right) / 2);
+    if (mid === 0 || numbers[mid - 1] >= mid) {
+      if (mid === numbers.length || numbers[mid] < mid) {
+        return mid;
+      }
+      left = mid + 1;
+    } else {
+      right = mid - 1;
+    }
+  }
+
+  return -1;
+}