└── binary search tree concepts


/binary search tree concepts:
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  1 | #include <bits/stdc++.h>
  2 | using namespace std;
  3 | 
  4 | class Node{
  5 |     public:
  6 |     Node* left;
  7 |     int key;
  8 |     Node* right;
  9 | };
 10 | Node* newNode(int data){
 11 |     Node* n=new Node();
 12 |     n->key=data;
 13 |     n->left=NULL;
 14 |     n->right=NULL;
 15 |     return n;
 16 | }
 17 | Node* insert(Node*root,int data){
 18 |     Node* nn=newNode(data);
 19 |     if(root==NULL){
 20 |         root=nn;
 21 |         return root;
 22 |     }
 23 |     else{
 24 |         queue<Node*>q;
 25 |         q.push(root);
 26 |         while(!q.empty()){
 27 |             Node* present=q.front();
 28 |             q.pop();
 29 |             if(present->left==NULL && present->key>nn->key){
 30 |                 present->left=nn;
 31 |                 break;
 32 |             }
 33 |             else{
 34 |                 q.push(present->left);
 35 |             }
 36 |             if(present->right==NULL && present->key<nn->key){
 37 |                 present->right=nn;
 38 |                 break;
 39 |             }
 40 |             else{
 41 |                 q.push(present->right);
 42 |             }
 43 |         }
 44 |     }
 45 |     return root;
 46 | }
 47 | Node* minimum(Node* root){
 48 |     if(root->left==NULL){
 49 |         return root;
 50 |     }
 51 |     else
 52 |      return minimum(root->left);
 53 | }
 54 | 
 55 | Node* deleteNode(Node* root,int data){
 56 |     if(root==NULL){
 57 |         cout<<"Value not found in BST";
 58 |         return NULL;
 59 |     }
 60 |     if(data<root->key){
 61 |         root->left=deleteNode(root->left,data);
 62 |     }
 63 |     else if(data>root->key){
 64 |         root->right=deleteNode(root->right,data);
 65 |     }
 66 |     else{
 67 |         if(root->left!=NULL&&root->right!=NULL){
 68 |             Node* temp=root;
 69 |             Node* minNodeForRight=minimum(temp->right);
 70 |             root->key=minNodeForRight->key;
 71 |             root->right=deleteNode(root->right,minNodeForRight->key);
 72 |         }
 73 |         else if(root->left!=NULL){
 74 |             root=root->left;
 75 |         }
 76 |         else if(root->right!=NULL){
 77 |             root=root->right;
 78 |         }
 79 |         else{
 80 |             root=NULL;
 81 |         }
 82 |     }
 83 |     return root;
 84 | }
 85 | //display function or level order
 86 | Node* display(Node* root){
 87 |     if(root==NULL){
 88 |         cout<<"Tree Empty";
 89 |     }
 90 |     queue<Node*>queue;
 91 |     queue.push(root);
 92 |     while(!queue.empty()){
 93 |         Node*front=queue.front();
 94 |         queue.pop();
 95 |         cout<<front->key<<"->";
 96 |         if(front->left!=NULL){
 97 |             queue.push(front->left);
 98 |         }
 99 |         if(front->right!=NULL){
100 |             queue.push(front->right);
101 |         }
102 |     }
103 |     cout<<"NULL";
104 |     return root;
105 | }
106 | 
107 | Node* search(Node* root, int data) {
108 |     if (root == NULL) {
109 |         cout << "Not Found  ";
110 |         return root;
111 |     }
112 |     else if (root->key == data) {
113 |         cout << "Found  ";
114 |     } else if (root->key>data) {
115 |         search(root->left, data);
116 |     } else {
117 |         root->right=search(root->right, data);
118 |     }
119 | }
120 | 
121 | 
122 | 
123 | int main() {
124 | 	Node* root=NULL;
125 | 	root=insert(root,54);
126 | 	root=insert(root,56);
127 | 	root=insert(root,7);
128 | 	root=insert(root,2);
129 | 	root=insert(root,70);
130 | 	root=insert(root,5);
131 | 	search(root,7);
132 | 	root=deleteNode(root,56);
133 | 	
134 | 	display(root);
135 | }
136 | 


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