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update trees
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‎Trees/.ipynb_checkpoints/Binary Search Trees-checkpoint.ipynb

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{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"# Binary Search Trees"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"This is the code ot go along with the video explanation. Check out the video lecture for full details!"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 5,
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"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"class TreeNode:\n",
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" \n",
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" def __init__(self,key,val,left=None,right=None,parent=None):\n",
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" self.key = key\n",
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" self.payload = val\n",
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" self.leftChild = left\n",
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" self.rightChild = right\n",
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" self.parent = parent\n",
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"\n",
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" def hasLeftChild(self):\n",
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" return self.leftChild\n",
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"\n",
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" def hasRightChild(self):\n",
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" return self.rightChild\n",
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"\n",
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" def isLeftChild(self):\n",
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" return self.parent and self.parent.leftChild == self\n",
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"\n",
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" def isRightChild(self):\n",
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" return self.parent and self.parent.rightChild == self\n",
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"\n",
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" def isRoot(self):\n",
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" return not self.parent\n",
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"\n",
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" def isLeaf(self):\n",
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" return not (self.rightChild or self.leftChild)\n",
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"\n",
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" def hasAnyChildren(self):\n",
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" return self.rightChild or self.leftChild\n",
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"\n",
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" def hasBothChildren(self):\n",
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" return self.rightChild and self.leftChild\n",
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"\n",
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" def replaceNodeData(self,key,value,lc,rc):\n",
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" self.key = key\n",
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" self.payload = value\n",
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" self.leftChild = lc\n",
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" self.rightChild = rc\n",
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" if self.hasLeftChild():\n",
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" self.leftChild.parent = self\n",
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" if self.hasRightChild():\n",
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" self.rightChild.parent = self\n",
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"\n",
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"\n",
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"class BinarySearchTree:\n",
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"\n",
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" def __init__(self):\n",
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" self.root = None\n",
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" self.size = 0\n",
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"\n",
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" def length(self):\n",
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" return self.size\n",
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"\n",
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" def __len__(self):\n",
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" return self.size\n",
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"\n",
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" def put(self,key,val):\n",
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" if self.root:\n",
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" self._put(key,val,self.root)\n",
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" else:\n",
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" self.root = TreeNode(key,val)\n",
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" self.size = self.size + 1\n",
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"\n",
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" def _put(self,key,val,currentNode):\n",
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" if key < currentNode.key:\n",
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" if currentNode.hasLeftChild():\n",
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" self._put(key,val,currentNode.leftChild)\n",
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" else:\n",
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" currentNode.leftChild = TreeNode(key,val,parent=currentNode)\n",
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" else:\n",
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" if currentNode.hasRightChild():\n",
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" self._put(key,val,currentNode.rightChild)\n",
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" else:\n",
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" currentNode.rightChild = TreeNode(key,val,parent=currentNode)\n",
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"\n",
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" def __setitem__(self,k,v):\n",
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" self.put(k,v)\n",
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"\n",
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" def get(self,key):\n",
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" if self.root:\n",
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" res = self._get(key,self.root)\n",
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" if res:\n",
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" \n",
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" return res.payload\n",
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" else:\n",
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" return None\n",
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" else:\n",
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" return None\n",
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"\n",
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" def _get(self,key,currentNode):\n",
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" \n",
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" if not currentNode:\n",
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" return None\n",
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" elif currentNode.key == key:\n",
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" return currentNode\n",
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" elif key < currentNode.key:\n",
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" return self._get(key,currentNode.leftChild)\n",
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" else:\n",
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" return self._get(key,currentNode.rightChild)\n",
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"\n",
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" def __getitem__(self,key):\n",
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" return self.get(key)\n",
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"\n",
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" def __contains__(self,key):\n",
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" if self._get(key,self.root):\n",
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" return True\n",
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" else:\n",
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" return False\n",
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"\n",
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" def delete(self,key):\n",
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" \n",
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" if self.size > 1:\n",
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" \n",
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" nodeToRemove = self._get(key,self.root)\n",
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" if nodeToRemove:\n",
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" self.remove(nodeToRemove)\n",
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" self.size = self.size-1\n",
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" else:\n",
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" raise KeyError('Error, key not in tree')\n",
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" elif self.size == 1 and self.root.key == key:\n",
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" self.root = None\n",
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" self.size = self.size - 1\n",
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" else:\n",
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" raise KeyError('Error, key not in tree')\n",
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"\n",
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" def __delitem__(self,key):\n",
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" \n",
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" self.delete(key)\n",
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"\n",
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" def spliceOut(self):\n",
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" if self.isLeaf():\n",
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" if self.isLeftChild():\n",
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" \n",
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" self.parent.leftChild = None\n",
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" else:\n",
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" self.parent.rightChild = None\n",
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" elif self.hasAnyChildren():\n",
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" if self.hasLeftChild():\n",
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" \n",
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" if self.isLeftChild():\n",
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" \n",
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" self.parent.leftChild = self.leftChild\n",
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" else:\n",
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" \n",
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" self.parent.rightChild = self.leftChild\n",
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" self.leftChild.parent = self.parent\n",
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" else:\n",
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" \n",
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" if self.isLeftChild():\n",
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" \n",
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" self.parent.leftChild = self.rightChild\n",
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" else:\n",
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" self.parent.rightChild = self.rightChild\n",
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" self.rightChild.parent = self.parent\n",
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"\n",
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" def findSuccessor(self):\n",
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" \n",
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" succ = None\n",
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" if self.hasRightChild():\n",
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" succ = self.rightChild.findMin()\n",
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" else:\n",
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" if self.parent:\n",
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" \n",
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" if self.isLeftChild():\n",
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" \n",
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" succ = self.parent\n",
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" else:\n",
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" self.parent.rightChild = None\n",
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" succ = self.parent.findSuccessor()\n",
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" self.parent.rightChild = self\n",
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" return succ\n",
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"\n",
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" def findMin(self):\n",
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" \n",
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" current = self\n",
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" while current.hasLeftChild():\n",
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" current = current.leftChild\n",
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" return current\n",
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"\n",
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" def remove(self,currentNode):\n",
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" \n",
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" if currentNode.isLeaf(): #leaf\n",
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" if currentNode == currentNode.parent.leftChild:\n",
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" currentNode.parent.leftChild = None\n",
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" else:\n",
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" currentNode.parent.rightChild = None\n",
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" elif currentNode.hasBothChildren(): #interior\n",
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" \n",
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" succ = currentNode.findSuccessor()\n",
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" succ.spliceOut()\n",
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" currentNode.key = succ.key\n",
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" currentNode.payload = succ.payload\n",
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"\n",
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" else: # this node has one child\n",
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" if currentNode.hasLeftChild():\n",
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" if currentNode.isLeftChild():\n",
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" currentNode.leftChild.parent = currentNode.parent\n",
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" currentNode.parent.leftChild = currentNode.leftChild\n",
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" elif currentNode.isRightChild():\n",
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" currentNode.leftChild.parent = currentNode.parent\n",
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" currentNode.parent.rightChild = currentNode.leftChild\n",
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" else:\n",
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" \n",
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" currentNode.replaceNodeData(currentNode.leftChild.key,\n",
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" currentNode.leftChild.payload,\n",
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" currentNode.leftChild.leftChild,\n",
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" currentNode.leftChild.rightChild)\n",
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" else:\n",
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" \n",
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" if currentNode.isLeftChild():\n",
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" currentNode.rightChild.parent = currentNode.parent\n",
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" currentNode.parent.leftChild = currentNode.rightChild\n",
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" elif currentNode.isRightChild():\n",
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" currentNode.rightChild.parent = currentNode.parent\n",
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" currentNode.parent.rightChild = currentNode.rightChild\n",
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" else:\n",
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" currentNode.replaceNodeData(currentNode.rightChild.key,\n",
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" currentNode.rightChild.payload,\n",
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" currentNode.rightChild.leftChild,\n",
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" currentNode.rightChild.rightChild)\n",
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"\n",
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"\n"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 6,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"yellow\n",
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"at\n"
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]
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}
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],
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"source": [
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"mytree = BinarySearchTree()\n",
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"mytree[3]=\"red\"\n",
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"mytree[4]=\"blue\"\n",
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"mytree[6]=\"yellow\"\n",
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"mytree[2]=\"at\"\n",
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"\n",
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"print(mytree[6])\n",
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"print(mytree[2])"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"** Check the video for full explanation! **"
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]
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}
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],
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"metadata": {
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"kernelspec": {
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"display_name": "Python 2",
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"language": "python",
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"name": "python2"
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},
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"language_info": {
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"codemirror_mode": {
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"name": "ipython",
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"version": 2
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},
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython2",
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"version": "2.7.11"
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}
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},
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"nbformat": 4,
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"nbformat_minor": 0
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}

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