Create BST.js

Author: shreyanshchordia

Binary-Search-Tree_8/BST.js

@@ -0,0 +1,203 @@
+/*
+This code explains, how can Javascript be used to implement Binary Search Trees.
+In this program I have written code to add elements to a binary search tree, run in-order,
+pre-order, post-order traversals and find elements in a BST.
+*/
+class Node{
+    constructor(val){
+        this.val = val
+        this.left = null
+        this.right = null
+        this.count = 1
+    }
+}
+
+class BinarySearchTree{
+    constructor(){
+        this.root = null
+    }
+
+    create(val){
+        var newnode = new Node(val)
+        return newnode
+    }
+
+    add(val){
+        var newnode = this.create(val)
+        if (!this.root){
+            this.root = newnode
+            return
+        }
+
+        else{
+            var prev = null
+            var temp = this.root
+            while(temp){
+                prev = temp
+
+                if (val == temp.val){
+                    temp.count += 1
+                    return
+                }
+                else if (val < temp.val){
+                    temp = temp.left
+                }
+                else{
+                    temp = temp.right
+                }
+            }
+
+            if (val > prev.val){
+                prev.right = newnode
+            }
+
+            else {
+                prev.left = newnode
+            }
+
+            return
+        }
+    }
+
+    inorder(temp){
+        if(!temp){
+            return
+        }
+
+        else{
+            this.inorder(temp.left)
+
+            for (let index = 0; index < temp.count; index++) {
+                console.log(temp.val + " ")
+            }
+
+            this.inorder(temp.right)
+            return
+        }
+    }
+
+    inorder_traversal(){
+        this.inorder(this.root)
+    }
+
+    postorder(temp){
+        if(!temp){
+            return
+        }
+
+        else{
+            this.postorder(temp.left)
+    
+            this.postorder(temp.right)
+
+            for (let index = 0; index < temp.count; index++) {
+                console.log(temp.val + " ")
+            }
+
+            return
+        }
+    }
+
+    postorder_traversal(){
+        this.postorder(this.root)
+    }
+
+    preorder(temp){
+        if(!temp){
+            return
+        }
+
+        else{
+
+            for (let index = 0; index < temp.count; index++) {
+                console.log(temp.val + " ")
+            }
+            
+            this.preorder(temp.left)
+
+            this.preorder(temp.right)
+            return
+        }
+    }
+
+    preorder_traversal(){
+        this.preorder(this.root)
+    }
+
+    find_val(val, temp){
+        if(!temp){
+            return -1
+        }
+
+        else{
+            if(val == temp.val){
+                return temp.count
+            }
+            else if (val < temp.val){
+                return this.find_val(val, temp.left)
+            }
+            else{
+                return this.find_val(val, temp.right)
+            }
+        }
+    }
+
+    find(val){
+        return this.find_val(val, this.root)
+    }
+
+}
+
+
+var tree = new BinarySearchTree()
+
+tree.add(1)
+tree.add(5)
+tree.add(2)
+tree.add(4)
+tree.add(2)
+tree.add(3)
+console.log("# Inorder Traversal")
+tree.inorder_traversal()
+console.log("# Pre-order Traversal")
+tree.preorder_traversal()
+console.log("# Post-order Traversal")
+tree.postorder_traversal()
+console.log("# Finding 10")
+console.log(tree.find(10))
+console.log("# Finding 2")
+console.log(tree.find(2))
+console.log("# Finding 5")
+console.log(tree.find(5))
+
+/*
+OUTPUT
+
+# Inorder Traversal
+1
+2
+2
+3
+4
+5
+# Pre-order Traversal
+1
+5
+2
+2
+4
+3
+# Post-order Traversal
+3
+4
+2
+2
+5
+1
+# Finding 10
+-1
+# Finding 2
+2
+# Finding 5
+1
+*/