4_hash_table_collision_handling.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 56,
   "metadata": {},
   "outputs": [],
   "source": [
    "class HashTable:  \n",
    "    def __init__(self):\n",
    "        self.MAX = 10\n",
    "        self.arr = [None for i in range(self.MAX)]\n",
    "        \n",
    "    def get_hash(self, key):\n",
    "        hash = 0\n",
    "        for char in key:\n",
    "            hash += ord(char)\n",
    "        return hash % self.MAX\n",
    "    \n",
    "    def __getitem__(self, index):\n",
    "        h = self.get_hash(index)\n",
    "        return self.arr[h]\n",
    "    \n",
    "    def __setitem__(self, key, val):\n",
    "        h = self.get_hash(key)\n",
    "        self.arr[h] = val    "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 51,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "9"
      ]
     },
     "execution_count": 51,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "t = HashTable()\n",
    "t.get_hash(\"march 6\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "scrolled": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "9"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "t.get_hash(\"march 17\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 54,
   "metadata": {},
   "outputs": [],
   "source": [
    "t[\"march 6\"] = 120\n",
    "t[\"march 8\"] = 67\n",
    "t[\"march 9\"] = 4\n",
    "t[\"march 17\"] = 459"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 55,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "459"
      ]
     },
     "execution_count": 55,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "t[\"march 6\"]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<h2>Hash Table Collision Handling Using Chaining</h2>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 86,
   "metadata": {},
   "outputs": [],
   "source": [
    "class HashTable:  \n",
    "    def __init__(self):\n",
    "        self.MAX = 10\n",
    "        self.arr = [[] for i in range(self.MAX)]\n",
    "        \n",
    "    def get_hash(self, key):\n",
    "        hash = 0\n",
    "        for char in key:\n",
    "            hash += ord(char)\n",
    "        return hash % self.MAX\n",
    "    \n",
    "    def __getitem__(self, key):\n",
    "        arr_index = self.get_hash(key)\n",
    "        for kv in self.arr[arr_index]:\n",
    "            if kv[0] == key:\n",
    "                return kv[1]\n",
    "            \n",
    "    def __setitem__(self, key, val):\n",
    "        h = self.get_hash(key)\n",
    "        found = False\n",
    "        for idx, element in enumerate(self.arr[h]):\n",
    "            if len(element)==2 and element[0] == key:\n",
    "                self.arr[h][idx] = (key,val)\n",
    "                found = True\n",
    "        if not found:\n",
    "            self.arr[h].append((key,val))\n",
    "        \n",
    "    def __delitem__(self, key):\n",
    "        arr_index = self.get_hash(key)\n",
    "        for index, kv in enumerate(self.arr[arr_index]):\n",
    "            if kv[0] == key:\n",
    "                print(\"del\",index)\n",
    "                del self.arr[arr_index][index]\n",
    "        "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 87,
   "metadata": {},
   "outputs": [],
   "source": [
    "t = HashTable()\n",
    "t[\"march 6\"] = 310\n",
    "t[\"march 7\"] = 420\n",
    "t[\"march 8\"] = 67\n",
    "t[\"march 17\"] = 63457"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 88,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "310"
      ]
     },
     "execution_count": 88,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "t[\"march 6\"]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 89,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "63457"
      ]
     },
     "execution_count": 89,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "t[\"march 17\"]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 90,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[[('march 7', 420)],\n",
       " [('march 8', 67)],\n",
       " [],\n",
       " [],\n",
       " [],\n",
       " [],\n",
       " [],\n",
       " [],\n",
       " [],\n",
       " [('march 6', 310), ('march 17', 63457)]]"
      ]
     },
     "execution_count": 90,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "t.arr"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 91,
   "metadata": {
    "scrolled": true
   },
   "outputs": [],
   "source": [
    "t[\"march 6\"] = 11"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 92,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[[('march 7', 420)],\n",
       " [('march 8', 67)],\n",
       " [],\n",
       " [],\n",
       " [],\n",
       " [],\n",
       " [],\n",
       " [],\n",
       " [],\n",
       " [('march 6', 11), ('march 17', 63457)]]"
      ]
     },
     "execution_count": 92,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "t.arr"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 68,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "310"
      ]
     },
     "execution_count": 68,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "t[\"march 6\"]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 48,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "del 0\n"
     ]
    }
   ],
   "source": [
    "del t[\"march 6\"]"
   ]
  }
 ],
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