BST and fun with trees

Whiteboard.ipynb

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+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "class Tree():\n",
+    "    def __init__(self, value):\n",
+    "        self.value = value\n",
+    "        self.right = None\n",
+    "        self.left = None\n",
+    "\n",
+    "TreeBST = Tree(100)\n",
+    "TreeBST.left = Tree(50)\n",
+    "TreeBST.left.left = Tree(25)\n",
+    "TreeBST.left.right = Tree (75)\n",
+    "TreeBST.right = Tree(200)\n",
+    "TreeBST.right.left = Tree(125)\n",
+    "TreeBST.right.right = Tree(350)\n"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 9,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "counter = 0\n",
+    "def findNthHighestInBST(root, n):\n",
+    "    if root is None:\n",
+    "        return None\n",
+    "    \n",
+    "    result = findNthHighestInBST(root.right, n)\n",
+    "    if result is not None:\n",
+    "        return result\n",
+    "    \n",
+    "    global counter\n",
+    "    \n",
+    "    counter += 1\n",
+    "    if counter == n:\n",
+    "        return root.value\n",
+    "    \n",
+    "    result = findNthHighestInBST(root.left, n)\n",
+    "    if result is not None:\n",
+    "        return result\n",
+    "    \n",
+    "    return None\n",
+    "\n",
+    "# print (findNthHighestInBST(TreeBST, 3))"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 10,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "def MirrorTree(root):\n",
+    "    if root is None:\n",
+    "        return\n",
+    "    \n",
+    "    MirrorTree(root.left)\n",
+    "    MirrorTree(root.right)\n",
+    "    root.left, root.right = root.right, root.right\n",
+    "    \n",
+    "    return root\n"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 17,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "from collections import deque\n",
+    "def DeleteZeroSumSubTrees(root):\n",
+    "    if root == None:\n",
+    "        return root\n",
+    "    \n",
+    "    if getSum(root) == 0:\n",
+    "        return None\n",
+    "    \n",
+    "    q = deque()\n",
+    "    q.append(root)\n",
+    "    while q:\n",
+    "        ele = q.popleft()\n",
+    "        if getSum(ele.left) == 0:\n",
+    "            ele.left = None\n",
+    "        if getSum(ele.right) == 0:\n",
+    "            ele.right = None\n",
+    "            \n",
+    "        if ele.left != None:\n",
+    "            q.append(ele.left)\n",
+    "        if ele.right != None:\n",
+    "            q.append(ele.right)\n",
+    "    \n",
+    "    return root\n",
+    "\n",
+    "def getSum(root):\n",
+    "    sum = 0\n",
+    "    if root == None:\n",
+    "        return sum\n",
+    "    \n",
+    "    sum += root.value + getSum(root.left) + getSum(root.right)\n",
+    "    return sum\n",
+    "\n",
+    "# print (DeleteZeroSumSubTrees(TreeBST).value)\n"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "def deleteZeroSumSubTrees2(root):\n",
+    "    if root != None:\n",
+    "        sum = deleteZeroSumSubTrees2Recursive(root)\n",
+    "        if sum == 0:\n",
+    "            root = None\n",
+    "    \n",
+    "    return root\n",
+    "\n",
+    "def deleteZeroSumSubTrees2Recursive(root):\n",
+    "    if root = None:\n",
+    "        return 0\n",
+    "    \n",
+    "    leftSum = deleteZeroSumSubTrees2Recursive(root.left)\n",
+    "    rightSum = deleteZeroSumSubTrees2Recursive(root.right)\n",
+    "    \n",
+    "    if leftSum == 0:\n",
+    "        root.left = None\n",
+    "            \n",
+    "    if rightSum == 0:\n",
+    "        root.right = None\n",
+    "    \n",
+    "    return root.value + leftSum + rightSum"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": []
+  }
+ ],
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