From d362b2761b2d14d5f7e85db6c807c17c7d5c3109 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Filipe=20Falc=C3=A3o?= <filipefalcaosantos@gmail.com>
Date: Sat, 23 May 2015 15:53:46 -0300
Subject: [PATCH] Handle collision in the HashMap #66

---
 src/data-structures/hash-table.js | 65 ++++++++++++++++++++++++++++---
 1 file changed, 59 insertions(+), 6 deletions(-)

diff --git a/src/data-structures/hash-table.js b/src/data-structures/hash-table.js
index 18a327f4..7ef4f63c 100644
--- a/src/data-structures/hash-table.js
+++ b/src/data-structures/hash-table.js
@@ -18,14 +18,21 @@
  * HashTable.remove(10);
  * HashTable.remove('key');
  *
- * console.log(HashTable.get(10)); // 'undefined'
- * console.log(HashTable.get('key')); // 'undefined'
+ * console.log(HashTable.get(10)); // null
+ * console.log(HashTable.get('key')); // null
  *
  * @module data-structures/hash-table
 */
 (function (exports) {
   'use strict';
 
+  exports.Node = function (key, data) {
+    this.key = key;
+    this.data = data;
+    this.next = null;
+    this.prev = null;
+  };
+
   exports.HashTable = function () {
     this.elements = [];
   };
@@ -41,25 +48,71 @@
 
     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) {
+  exports.HashTable.prototype.put = function (key, data) {
     var hashCode = this.hashCode(key);
-    this.elements[hashCode] = value;
+    var newNode = new Node(key, data);
+
+    if (this.elements[hashCode] === null) {
+      this.elements[hashCode] = newNode;
+    } else {
+      var first = this.elements[hashCode];
+
+      while (first.next !== null) {
+        first = first.next;
+      }
+
+      first.next = newNode;
+      newNode.prev = first;
+    }
   };
 
   exports.HashTable.prototype.get = function (key) {
     var hashCode = this.hashCode(key);
-    return this.elements[hashCode];
+
+    if (this.elements[hashCode] === null) {
+      return null;
+    } else if (this.elements[hashCode].next === null) {
+      return this.elements[hashCode];
+    } else {
+      var first = this.elements[hashCode];
+
+      while (first.key !== key) {
+        first = first.next;
+      }
+
+      return first;
+    }
   };
 
   exports.HashTable.prototype.remove = function (key) {
     var hashCode = this.hashCode(key);
-    this.elements.splice(hashCode, 1);
+
+    if (this.elements[hashCode] === null) {
+      return false;
+    } else if (this.elements[hashCode].next === null) {
+      this.elements.splice(hashCode, 1);
+      return true;
+    } else {
+      var first = this.elements[hashCode];
+
+      while (first.key !== key) {
+        first = first.next;
+      }
+
+      if (first.next !== null) {
+        first.next.prev = first.prev;
+      }
+
+      first.prev.next = first.next;
+    }
   };
 })(typeof window === 'undefined' ? module.exports : window);