Added BST sol

drivercode/BSTDriver.cpp

@@ -3,97 +3,264 @@
 #include<iostream>
 #include<vector>
 #include<stdlib.h>
-
+#include <algorithm> 
+#include <queue>
 
 using namespace std; 
 
 class TreeNode {
   public: 
   int val; 
   TreeNode * left; 
-  TreeNode * right; 
-  // Add constructor. 
+  TreeNode * right;
+
+  // Add constructor.
+  TreeNode(){
+
+    this->right = this->left  = NULL;
+  } 
+  TreeNode(int val){
+    this->val = val;
+    this->right = this->left  = NULL;
+  }
 }; 
 
 vector<int> generateRandomArray(int size) {
-  return vector<int>(size); 
+  vector<int> arr(size);
+  for(int i=0;i<size;i++){
+    arr[i] = rand() % 117;
+  }
+  return arr; 
 }
 
 int height(TreeNode * root) {
-  return 0; 
+  if(root == NULL)
+    return 0;
+  return max(height(root->left),height(root->right)) + 1;
+
+}
+void inorder(TreeNode* root){
+  if(root==NULL)
+    return;
+  inorder(root->left);
+  cout<<root->val<<" ";
+  inorder(root->right);
+  return;
+}
+void preorder(TreeNode* root){
+  if(root == NULL)
+    return;
+  cout<<root->val<<" ";
+  preorder(root->left);
+  preorder(root->right);
+  return;
+}
+void postorder(TreeNode * root){
+  if(root == NULL)
+    return;
+  postorder(root->left);
+  postorder(root->right);
+  cout<<root->val<<" ";
+  return;
 }
-
 void printTraversals(TreeNode * root) {
   // print inorder
+  cout<<"Inorder"<<endl;
+  inorder(root);
+  cout<<endl;
   // print preorder
+  cout<<"Preorder"<<endl;
+  preorder(root);
+  cout<<endl;
   // print postorder
+  cout<<"Postorder"<<endl;
+  postorder(root);
+  cout<<endl;
+  return;
 }
 
 
 // Return NULL if val not found. 
 TreeNode * search(TreeNode * root, int val) {
-  return NULL; 
+  if(root == NULL)
+    return root;
+  if(root->val == val)
+    return root;
+  if(root->val > val)
+    return search(root->left, val);
+
+  return search(root->right, val); 
 }
 
 // Return parent even if val is not present in tree. 
 // Basically return the parent of the location where val should have been.
 TreeNode* searchParent(TreeNode * root, int val) {
-  return NULL; 
+  if(root == NULL)
+    return root;
+
+  if(root->left != NULL and root->left->val == val)
+    return root;
+  if(root->right != NULL and root->right->val == val)
+    return root;
+  if(root->val>val)
+    return searchParent(root->left,val);
+  return searchParent(root->right,val);
 }
 
 
 TreeNode * insert(TreeNode * root, int val) {
-  return root; 
+  if (root == NULL) {
+      TreeNode* t=new TreeNode(val); 
+      return t;
+    }
+
+
+    if (val< root->val) {
+        root->left = insert(root->left, val);
+    }
+    else {
+        root->right = insert(root->right, val);
+    }
+
+    return root;
+
+
 }
 
 int maxValue(TreeNode * root) {
-  return INT_MAX; 
+  if(root->right == NULL)
+    return root->val;
+
+  return maxValue(root->right); 
 }
 
 int minValue(TreeNode * root) {
-  return INT_MIN; 
+  if(root->left == NULL)
+    return root->val;
+
+  return minValue(root->left);
 }
 
 // Return NULL if val has no successor, ie, val is greater than maxValue(root);  
 // Successor should be returned even if val is not present in the tree. 
-TreeNode * findSuccessor(TreeNode * root) {
-  return NULL;
+TreeNode * findSuccessor(TreeNode * root,TreeNode* Root) {
+
+  if(root == NULL)
+  { return root;}
+  if(root->right)
+    return search(root->right,minValue(root->right));
+  TreeNode * t = searchParent(Root,root->val);
+  while( t!=NULL and root == t->right){
+    root = t;
+    t = searchParent(Root,root->val);
+  }
+  return t;
 }
 
 // Return NULL if val has no predecessor, ie, val is smaller than minValue(root);  
 // Predecessor should be returned even if val is not present in the tree. 
-TreeNode * findPredecessor(TreeNode * root) {
-  return NULL;
+TreeNode * findPredecessor(TreeNode * root,TreeNode* Root) {
+  if(root == NULL)
+    return root;
+  if(root->left)
+    return search(root->left,maxValue(root->left));
+  TreeNode * t = searchParent(Root,root->val);
+  while( t!=NULL and root == t->left){
+    root = t;
+    t = searchParent(Root,root->val);
+  }
+  return t;
 }
 
 // First generate random array. Then build this tree by calling insert() on each element of array. 
 TreeNode * buildTree(vector<int> & v) {
   // Call insert() repeatedly to build the tree.
-  TreeNode * root = new TreeNode(); 
-  return root; 
+  TreeNode* root = NULL;
+  for(auto it:v)
+  { 
+    root = insert(root,it);
+  }
+  return root;
 }
+void LevelOrderBFS(TreeNode* root){
+  if(root == NULL)
+    return ;
+  queue<TreeNode*> q;
+  q.push(root);
+  q.push(NULL);
+  while(!q.empty()){
+    TreeNode* temp = q.front();
+    q.pop();
+    if(temp == NULL)
+    {
+      cout<<"\n";
+      if(!q.empty())
+        q.push(NULL);
+    }
+    else{
+      cout<<temp->val<<" ";
+      if(temp->left)
+        q.push(temp->left);
+      if(temp->right)
+        q.push(temp->right);
 
+    }
+
+  }
+  return;
+}
 
 
 int main() {
   // Study all tree algorithms from geeksforgeeks or this youtube video. 
   // https://www.youtube.com/watch?v=K6nw5TvhX2s&list=PLrYpW0KwQ3sMemsZOzhawxMpFet3Hb3SN&index=39
 
   // 1. Generate a random array. 
-  // 2. Create an empty tree and insert one value from the array at a time. 
-  // 3. Inorder traversal of this binary search tree should be equal to the sorted value of random array.   
+  vector<int> arr = generateRandomArray(10);
+  for(auto it:arr)
+    cout<<it<<" ";
+  cout<<"\n";
+  // 2. Create an empty tree and insert one value from the array at a time.
+  TreeNode* root = buildTree(arr);
+
+  // 3. Inorder traversal of this binary search tree should be equal to the sorted value of random array.  
+  printTraversals(root); 
   // 4. Find the height of the tree. 
+  // Level order
+  cout<<"Level Order"<<"\n";
+  LevelOrderBFS(root);
+  cout<<"Height of tree : "<< height(root)<<" \n";
 
-
-  // 5. Find the minimum value in the array. 
+  // 5. Find the minimum value in the array.
+  int mv = minValue(root); 
+  cout<<"Min value in tree : "<<mv<<"\n";
   // 6. In the tree, find successor of this value. Print it. Then find successor
+  TreeNode * temp = search(root,mv);
+
+  TreeNode * succ = findSuccessor(temp,root);
+
+  while(succ != NULL){
+  cout<<"successor of "<<temp->val<<" is "<<succ->val<<" \n";
+  temp = succ;
+  succ = findSuccessor(temp,root);
+  }
+
   //    of the value just obtained. Print again and so on. 
   // 7. This list should be equal to the sorted value of the array. 
 
   // 8. Find the maximum value in the array. 
+  int mx = maxValue(root);
+  cout<<"Max value in tree : "<<mx<<"\n";
   // 9. In the tree, find predecessor of this value. Print it. Then find predecessor
   //    of the value just obtained till no more predecessor exists. Print again and so on. 
   // 10. This list should be equal to the sorted value of the array. 
+  temp = search(root,mx);
+  TreeNode * psucc = findPredecessor(temp,root);
+  while(psucc != NULL){
+  cout<<"Presuccessor of "<<temp->val<<" is "<<psucc->val<<" \n";
+  temp = psucc;
+  psucc = findPredecessor(temp,root);
+  }
 
 
 }