Add solution #706

Author: JoshCrozier

README.md

@@ -134,6 +134,7 @@
 700|[Search in a Binary Search Tree](./0700-search-in-a-binary-search-tree.js)|Easy|
 701|[Insert into a Binary Search Tree](./0701-insert-into-a-binary-search-tree.js)|Medium|
 704|[Binary Search](./0704-binary-search.js)|Easy|
+706|[Design HashMap](./0706-design-hashmap.js)|Easy|
 713|[Subarray Product Less Than K](./0713-subarray-product-less-than-k.js)|Medium|
 722|[Remove Comments](./0722-remove-comments.js)|Medium|
 733|[Flood Fill](./0733-flood-fill.js)|Easy|

solutions/0706-design-hashmap.js

@@ -0,0 +1,54 @@
+/**
+ * 706. Design HashMap
+ * https://leetcode.com/problems/design-hashmap/
+ * Difficulty: Easy
+ *
+ * Design a HashMap without using any built-in hash table libraries.
+ * Implement the MyHashMap class:
+ * - MyHashMap() initializes the object with an empty map.
+ * - void put(int key, int value) inserts a (key, value) pair into the HashMap.
+ *   If the key already exists in the map, update the corresponding value.
+ * - int get(int key) returns the value to which the specified key is mapped,
+ *   or -1 if this map contains no mapping for the key.
+ * - void remove(key) removes the key and its corresponding value if the map
+ *   contains the mapping for the key.
+ */
+
+
+var MyHashMap = function() {
+  this._keys = [];
+  this._values = [];
+};
+
+/**
+ * @param {number} key
+ * @param {number} value
+ * @return {void}
+ */
+MyHashMap.prototype.put = function(key, value) {
+  if (this._keys[key] === undefined) {
+    this._values.push(value);
+    this._keys[key] = this._values.length - 1;
+  } else {
+    this._values[this._keys[key]] = value;
+  }
+};
+
+/**
+ * @param {number} key
+ * @return {number}
+ */
+MyHashMap.prototype.get = function(key) {
+  const offset = this._keys[key];
+  return offset === undefined ? -1 : this._values[offset];
+}
+/**
+ * @param {number} key
+ * @return {void}
+ */
+MyHashMap.prototype.remove = function(key) {
+  if (this._keys[key] !== undefined) {
+    this._values[this._keys[key]] = undefined;
+    this._keys[key] = undefined;
+  }
+};