Add solution #380

Author: JoshCrozier

README.md

@@ -249,6 +249,7 @@
 371|[Sum of Two Integers](./0371-sum-of-two-integers.js)|Medium|
 372|[Super Pow](./0372-super-pow.js)|Medium|
 374|[Guess Number Higher or Lower](./0374-guess-number-higher-or-lower.js)|Medium|
+380|[Insert Delete GetRandom O(1)](./0380-insert-delete-getrandom-o1.js)|Medium|
 383|[Ransom Note](./0383-ransom-note.js)|Easy|
 387|[First Unique Character in a String](./0387-first-unique-character-in-a-string.js)|Easy|
 389|[Find the Difference](./0389-find-the-difference.js)|Easy|

solutions/0380-insert-delete-getrandom-o1.js

@@ -0,0 +1,52 @@
+/**
+ * 380. Insert Delete GetRandom O(1)
+ * https://leetcode.com/problems/insert-delete-getrandom-o1/
+ * Difficulty: Medium
+ *
+ * Implement the RandomizedSet class:
+ * - RandomizedSet() Initializes the RandomizedSet object.
+ * - bool insert(int val) Inserts an item val into the set if not present. Returns true if the
+ *   item was not present, false otherwise.
+ * - bool remove(int val) Removes an item val from the set if present. Returns true if the item
+ *   was present, false otherwise.
+ * - int getRandom() Returns a random element from the current set of elements (it's guaranteed
+ *   that at least one element exists when this method is called). Each element must have the
+ *   same probability of being returned.
+ *
+ * You must implement the functions of the class such that each function works in average O(1)
+ * time complexity.
+ */
+
+
+var RandomizedSet = function() {
+  this.set = new Set();
+};
+
+/**
+ * @param {number} val
+ * @return {boolean}
+ */
+RandomizedSet.prototype.insert = function(val) {
+  const hasValue = this.set.has(val);
+  this.set.add(val);
+  return !hasValue;
+};
+
+/**
+ * @param {number} val
+ * @return {boolean}
+ */
+RandomizedSet.prototype.remove = function(val) {
+  const hasValue = this.set.has(val);
+  this.set.delete(val);
+  return hasValue;
+};
+
+/**
+ * @return {number}
+ */
+RandomizedSet.prototype.getRandom = function() {
+  const item = Array.from(this.set);
+  const randomIndex = Math.floor(Math.random() * item.length);
+  return item[randomIndex];
+};