Merge pull request tarunsinghofficial#1928 from Sumant03/TreesImporta…

…ntQuestions

TreesImportantQuestions

Java_Programs_for_beginners/Trees/DiameterOfBTree.java

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+
+import java.io.*;
+import java.util.*;
+
+public class DiameterOfBTree {
+  public static class Node {
+    int data;
+    Node left;
+    Node right;
+
+    Node(int data, Node left, Node right) {
+      this.data = data;
+      this.left = left;
+      this.right = right;
+    }
+  }
+
+  public static class Pair {
+    Node node;
+    int state;
+
+    Pair(Node node, int state) {
+      this.node = node;
+      this.state = state;
+    }
+  }
+
+  public static Node construct(Integer[] arr) {
+    Node root = new Node(arr[0], null, null);
+    Pair rtp = new Pair(root, 1);
+
+    Stack<Pair> st = new Stack<>();
+    st.push(rtp);
+
+    int idx = 0;
+    while (st.size() > 0) {
+      Pair top = st.peek();
+      if (top.state == 1) {
+        idx++;
+        if (arr[idx] != null) {
+          top.node.left = new Node(arr[idx], null, null);
+          Pair lp = new Pair(top.node.left, 1);
+          st.push(lp);
+        } else {
+          top.node.left = null;
+        }
+
+        top.state++;
+      } else if (top.state == 2) {
+        idx++;
+        if (arr[idx] != null) {
+          top.node.right = new Node(arr[idx], null, null);
+          Pair rp = new Pair(top.node.right, 1);
+          st.push(rp);
+        } else {
+          top.node.right = null;
+        }
+
+        top.state++;
+      } else {
+        st.pop();
+      }
+    }
+
+    return root;
+  }
+
+  public static void display(Node node) {
+    if (node == null) {
+      return;
+    }
+
+    String str = "";
+    str += node.left == null ? "." : node.left.data + "";
+    str += " <- " + node.data + " -> ";
+    str += node.right == null ? "." : node.right.data + "";
+    System.out.println(str);
+
+    display(node.left);
+    display(node.right);
+  }
+
+  public static int height(Node node) {
+    if (node == null) {
+      return -1;
+    }
+
+    int lh = height(node.left);
+    int rh = height(node.right);
+
+    int th = Math.max(lh, rh) + 1;
+    return th;
+  }
+  static int diaOfTree;
+  public static int diameter1(Node node) {
+    // write your code here
+    if(node==null){
+        return -1;
+    }
+
+    int lh=diameter1(node.left);
+    int rh=diameter1(node.right);
+
+    int diaOfNode=lh+rh+2;
+    if(diaOfNode>diaOfTree){
+        diaOfTree=diaOfNode;
+    }
+
+    return Math.max(lh,rh)+1;
+
+  }
+  public static int diameter2(Node node){
+     if(node==null){
+         return 0;
+     }   
+      int ldia=diameter2(node.left);
+      int rdia=diameter2(node.right);
+
+
+      int lh=height(node.left);
+      int rh=height(node.right);
+      int diaofNode=lh+rh+2;
+
+      return Math.max(diaofNode,Math.max(ldia,rdia));
+
+  }
+  public static class DiaPair{
+      int ht,dia;
+      DiaPair(int ht,int dia){
+          this.ht=ht;
+          this.dia=dia;
+      }
+  }
+  public static DiaPair diameter3(Node node){
+      if(node==null){
+          return new DiaPair(-1,0);
+          }
+        DiaPair lpair=diameter3(node.left);
+        DiaPair rpair=diameter3(node.right);
+
+        int ht=Math.max(lpair.ht,rpair.ht)+1;
+        int diaOfNode=lpair.ht+rpair.ht+2;
+        int diaofTree=Math.max(Math.max(lpair.dia,rpair.dia),diaOfNode);
+
+        return new DiaPair(ht,diaofTree);
+
+
+  }
+
+
+
+  public static void main(String[] args) throws Exception {
+    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    int n = Integer.parseInt(br.readLine());
+    Integer[] arr = new Integer[n];
+    String[] values = br.readLine().split(" ");
+    for (int i = 0; i < n; i++) {
+      if (values[i].equals("n") == false) {
+        arr[i] = Integer.parseInt(values[i]);
+      } else {
+        arr[i] = null;
+      }
+    }
+
+    Node root = construct(arr);
+
+    //  diaOfTree = 0;
+    //  diameter1(root);
+    // System.out.println(diaOfTree);
+
+    // System.out.println(diameter2(root));
+    DiaPair res=diameter3(root);
+    System.out.println(res.dia);
+
+  }
+
+}

Java_Programs_for_beginners/Trees/InOrderMorrisTraversal.java

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+import java.util.*;
+
+public class Main {
+  public static Scanner scn = new Scanner(System.in);
+
+  public static class TreeNode {
+    int val = 0;
+    TreeNode left = null;
+    TreeNode right = null;
+
+    TreeNode(int val) {
+      this.val = val;
+    }
+  }
+
+  public static TreeNode rightMostNode(TreeNode lc,TreeNode curr){
+      TreeNode rmn=lc;
+      while(rmn.right!=null&&rmn.right!=curr){
+          rmn=rmn.right;
+      }
+
+      return rmn;
+  }
+
+  public static ArrayList<Integer> morrisInTraversal(TreeNode node) {
+    ArrayList<Integer> ans=new ArrayList<>();
+
+    TreeNode curr=node;
+
+    while(curr!=null){
+
+        TreeNode lc=curr.left;
+        if(lc==null){
+            ans.add(curr.val);
+            curr=curr.right;
+        }else{
+            TreeNode rmn=rightMostNode(lc,curr);
+            if(rmn.right==null){
+                rmn.right=curr;
+                curr=curr.left;
+            }else if(rmn.right==curr){
+
+                ans.add(curr.val);
+                rmn.right=null;
+                curr=curr.right;
+            }
+        }
+
+    }
+    return ans;
+  }
+
+  // input_section=================================================
+
+  public static TreeNode createTree(int[] arr, int[] IDX) {
+    if (IDX[0] > arr.length || arr[IDX[0]] == -1) {
+      IDX[0]++;
+      return null;
+    }
+    TreeNode Treenode = new TreeNode(arr[IDX[0]++]);
+    Treenode.left = createTree(arr, IDX);
+    Treenode.right = createTree(arr, IDX);
+
+    return Treenode;
+  }
+
+  public static void solve() {
+    int n = scn.nextInt();
+    int[] arr = new int[n];
+    for (int i = 0; i < n; i++)
+      arr[i] = scn.nextInt();
+
+    int[] IDX = new int[1];
+    TreeNode root = createTree(arr, IDX);
+
+    ArrayList<Integer> ans = morrisInTraversal(root);
+    for (Integer i : ans)
+      System.out.print(i + " ");
+
+  }
+
+  public static void main(String[] args) {
+    solve();
+  }
+}