Merge pull request #137 from Shreyansh-Agrawal/patch-1

Binary Search Tree implementation in C++

BST_operations.cpp

@@ -0,0 +1,145 @@
+#include<iostream>
+using namespace std;
+
+class node{
+    public:
+        int data;
+        node *left, *right;
+
+        node(int data){
+            this->data = data;
+            left = NULL;
+            right = NULL;
+        }
+};
+
+    node* insertBST(node* root, int val){
+
+        if(root == NULL)
+            return new node(val);
+
+        if(val<root->data)
+            root->left = insertBST(root->left, val);
+        else
+            root->right = insertBST(root->right, val);
+
+        return root;
+    }
+
+    void inorder(node* root){
+        if(root == NULL) return;
+
+        inorder(root->left);
+        cout<<root->data<<" ";
+        inorder(root->right);
+    }
+
+    node* searchInBST(node* root, int key){
+
+        if(root == NULL) return NULL;
+
+        if(root->data == key) return root;
+
+        // data>key
+        if(root->data > key) return searchInBST(root->left, key);
+
+        //data<key
+        return searchInBST(root->right, key);
+    }
+
+    node* inorderSucc(node* root){
+        node* curr = root;
+
+        while(curr && curr->left != NULL)
+            curr = curr->left;
+
+        return curr;
+    }
+
+    node* deleteInBST(node* root, int val){
+
+        if(val < root->data)
+            root->left = deleteInBST(root->left, val);
+
+        else if(val > root->data)
+            root->right = deleteInBST(root->right, val);
+
+        else{
+            if(root->left == NULL){
+                node* temp = root->right;
+                free(root);
+                return temp;
+            }
+            else if(root->right == NULL){
+                node* temp = root->left;
+                free(root);
+                return temp;
+            }
+            //case 3
+            node* temp = inorderSucc(root->right);
+            root->data = temp->data;
+            root->right = deleteInBST(root->right, temp->data);
+        }
+        return root;
+    }
+
+int main(){
+
+    node *root = NULL;
+
+/*
+        4
+      /   \
+     2     5
+    / \     \
+   1   3     7
+*/
+    int option;
+    int data;
+
+    while(true){
+
+        cout<<"\n1. Create a Node  2. Insert  3. Display (In-order)  4. Search  5. Delete  0. Exit"<<endl;
+        cin>>option;
+
+        switch(option){
+            case 1:
+                cout<<"Enter the root data: ";
+                cin>>data;
+                root = insertBST(root, data);
+                break;
+
+            case 2:
+                cout<<"Enter the data: ";
+                cin>>data;
+                insertBST(root, data);
+                break;
+
+            case 3:
+                inorder(root);
+                cout<<endl;
+                break;
+
+            case 4:
+                cout<<"Enter the key: ";
+                cin>>data;
+                if(searchInBST(root, data) == NULL) 
+                    cout<<"Does not exists"<<endl;
+                else
+                    cout<<"Exists"<<endl;
+                break;
+
+            case 5:
+                cout<<"Enter the value to be deleted: ";
+                cin>>data;
+                root = deleteInBST(root, data);
+                break;
+
+        }
+        if(option == 0){
+            break;
+        }
+    }
+
+    return 0;
+}