added bottom view of a tree in java

Author: GauravWalia19

Java/Data-Structures/TREES/BINARY-TREE/MISC/BottomView.java

@@ -0,0 +1,126 @@
+import java.util.*;
+import java.util.Map.*;
+import java.util.Queue;
+abstract class BottomView
+{
+    /**
+     * BINARY TREE NODE STRUCTURE
+     **/
+    private static class BTNode
+    {
+        private int data;
+        private BTNode left;
+        private BTNode right;
+
+        //constructors
+        public BTNode(int data)
+        {
+            this.data=data;
+        }
+        //getters
+        public BTNode getLeft()
+        {
+            return left;
+        }
+        public BTNode getRight()
+        {
+            return right;
+        }
+        public int getData()
+        {
+            return data;
+        }
+        //setters
+        public void setLeft(BTNode left)
+        {
+            this.left = left;
+        }
+        public void setRight(BTNode right)
+        {
+            this.right = right;
+        }
+    }
+
+    /**
+     * BOTTOM VIEW OF A TREE
+     **/
+    public static void bottomview(BTNode root)
+    {
+        /**
+         * NEW quenode CLASS FOR A QUEUE
+         **/
+        final class quenode
+        {
+            public BTNode data;
+            public int hd;
+            public quenode(BTNode data,int hd)
+            {
+                this.data = data;
+                this.hd = hd;
+            }
+        }
+        Queue<quenode> Q = new LinkedList<quenode>();
+        Q.add(new quenode(root,0));
+        Map<Integer,Integer> m = new TreeMap<Integer,Integer>();
+
+        while(!Q.isEmpty())
+        {
+            quenode temp = Q.poll();
+            
+            m.put(temp.hd, temp.data.getData());
+
+            if(temp.data.getLeft()!=null)
+            {
+                Q.add(new quenode(temp.data.getLeft(),temp.hd-1));
+            }
+            if(temp.data.getRight()!=null)
+            {
+                Q.add(new quenode(temp.data.getRight(),temp.hd+1));
+            }
+        }
+
+        //traversing the map
+        for(Entry<Integer,Integer> entry: m.entrySet())
+        {
+            System.out.print(entry.getValue()+" ");
+        }
+        System.out.println();
+    }
+
+    /**
+     * TREE EXAMPLE GIVEN
+     *           20  <- ROOT
+     *         /    \
+     *        8      22
+     *       / \      \
+     *      5   3      25
+     *         / \
+     *        10 14  
+     * 
+     * BOTTOM VIEW : 5 10 3 14 25 
+     * */
+    public static void main(String[] args) 
+    {
+        BTNode a = new BTNode(20);
+        BTNode b = new BTNode(8);
+        BTNode c = new BTNode(22);
+        BTNode d = new BTNode(5);
+        BTNode e = new BTNode(3);
+        BTNode f = new BTNode(25);
+        BTNode g = new BTNode(10);
+        BTNode h = new BTNode(14);
+
+        BTNode root = a;
+        a.setLeft(b);
+        a.setRight(c);
+
+        b.setLeft(d);
+        b.setRight(e);
+        
+        e.setLeft(g);
+        e.setRight(h);
+        
+        c.setRight(f);
+        bottomview(root);
+    }
+}

Java/README.md

@@ -98,6 +98,11 @@
   * Breadth First Search
     * LEVEL ORDER
       * [ITERATIVE](Data-Structures/TREES/BINARY-TREE/LevelOrder.java)
+* MISC
+  * Bottom View of a Tree
+    * [ITERATIVE](Data-Structures/TREES/BINARY-TREE/MISC/BottomView.java)
+
+##### BINARY SEARCH TREES
 
 #### GRAPHS
 

datastructures.md

@@ -368,6 +368,16 @@ Indexer for Data Structures Lover
   * ITERATIVE
     * [JAVA](Java/Data-Structures/TREES/BINARY-TREE/LevelOrder.java)
 
+#### MISC
+
+##### BOTTOM VIEW OF A TREE
+
+* blog
+* docs
+* implementation
+  * [ITERATIVE](Java/Data-Structures/TREES/BINARY-TREE/MISC/BottomView.java)
+* [complexity](docs/complexity.md#binary-trees)
+
 ### GENERIC TREES
 
 ### THREADED BINARY TREE

docs/complexity.md

@@ -579,6 +579,7 @@ SNo. | Operations | Order and Type of Time Complexity O(n) | Order and Type of S
  2 | Pre Order Traversal | O(n) -- Linear | O(n) -- Linear | :heavy_check_mark: | :heavy_check_mark:
  3 | Post Order Traversal | O(n) -- Linear | O(n) -- Linear | :heavy_check_mark: | :heavy_check_mark:
  4 | Level Order Traversal | O(n) -- Linear | O(n) -- Linear | :heavy_check_mark: | :x:
+ 5 | Bottom View of a Tree | O(n) -- Linear | O(n) -- Linear | :heavy_check_mark: | :x:
 
 #### GENERIC TREES