Merge pull request mgechev#63 from mgechev/pr/62

Hash Table data structure

Author: JakeHP

src/data-structures/hash-table.js

@@ -0,0 +1,67 @@
+/**
+ * Hash Table
+ *
+ * An associative array, that can map keys
+ * (strings and numbers) to values in O(1).
+ *
+ * @example
+ * var hash = require('path-to-algorithms/src/data-structures'+
+ * '/hash-table');
+ * var HashTable = new hash.HashTable();
+ *
+ * HashTable.put(10, 'value');
+ * HashTable.put('key', 10);
+ *
+ * console.log(HashTable.get(10)); // 'value'
+ * console.log(HashTable.get('key')); // 10
+ *
+ * HashTable.remove(10);
+ * HashTable.remove('key');
+ *
+ * console.log(HashTable.get(10)); // 'undefined'
+ * console.log(HashTable.get('key')); // 'undefined'
+ *
+ * @module data-structures/hash-table
+*/
+(function (exports) {
+  'use strict';
+
+  exports.HashTable = function () {
+    this.elements = [];
+  };
+
+  exports.HashTable.prototype.hashCode = function (str) {
+    var i;
+    var hashCode = 0;
+    var character;
+
+    if (str.length === 0) {
+      return hashCode;
+    }
+
+    for (i = 0; i < str.length; i += 1) {
+      character = str.charCodeAt(i);
+      /*jshint -W016 */
+      hashCode = ((hashCode << 5) - hashCode) + character;
+      hashCode = hashCode & hashCode;
+      /*jshint -W016 */
+    }
+
+    return hashCode;
+  };
+
+  exports.HashTable.prototype.put = function (key, value) {
+    var hashCode = this.hashCode(key);
+    this.elements[hashCode] = value;
+  };
+
+  exports.HashTable.prototype.get = function (key) {
+    var hashCode = this.hashCode(key);
+    return this.elements[hashCode];
+  };
+
+  exports.HashTable.prototype.remove = function (key) {
+    var hashCode = this.hashCode(key);
+    this.elements.splice(hashCode, 1);
+  };
+})(typeof window === 'undefined' ? module.exports : window);