updated trees

Recursion/22. Regex and String Matching.cpp

@@ -0,0 +1,17 @@
+#include<iostream>
+using namespace std;
+
+
+int main(){
+char str[100],regExp[100];
+cout<<"Enter String & Regular Expression :";
+cin>>str;
+cin>>regExp;
+
+if(canAccept(regExp,str))
+    cout<<"String Accepted ! ";
+else
+    cout<<"Not Accepted ! ";
+
+return 0;
+}

Trees/15. Print BST elements in range K1 and K2.cpp

@@ -36,10 +36,10 @@ while(!q.empty()){
         }
         if(temp->right!=NULL){
             q.push(temp->right);
+            }
         }
     }
 }
-}
 
 //----------------------------------------------------Create from Array
 struct node*createBST(int *a,int low,int high){
@@ -87,45 +87,32 @@ else
    root->right = insert(root->right,data);
 return root;
 }
-//---------------------------------------------------------CHECK IF A BST OR NOT
-void PrintElementsInRange(struct node*root ,int k1,int k2){
-    if(root==NULL)
-        return NULL;
-
-
-    if(root->data>=k1)
-         { PrintElementsInRange(root->left,k1,k2);}
+//---------------------------------------Print elements in the range
+void printRange(struct node*root,int k1,int k2){
+if(root==NULL)
+    return;
 
-    else if(root->data>=k2)
-        {
+printRange(root->left,k1,k2);
 
 
-        }
-
+if(root->data >= k1&&root->data<=k2)
 
+    cout<<root->data<<" ";
 
+if(root->data>=k2)
+    { return ;}
 
+printRange(root->right,k1,k2);
 }
-
-//---------------------------------------Main
-
 int main(){
-int a[8]={1,2,6,4,5,6,7,9};
+int a[8]={1,1,3,4,5,6,7,9};
 struct node*root = NULL;
 root = createBST(a,0,7);
 cout<<"Originial "<<endl;
 insert(root,8);
-printLevelOrder(root);
-cout<<endl<<"Inorder : "<<endl;
-printPreorder(root);
-cout<<endl;
-if(isBST(root,-1000,1000))
-    cout<<"Dekh Bhai , Ye to BST Hi Hai ... !"<<endl;
-
-else{
-    cout<<"Na Bhai , BST nahin hai ... ! "<<endl;
-    }
+printRange(root,2,8); .
 return 0;
+
 }
 
 

Trees/18. Linked List to Balanced BST.cpp

@@ -1 +1,89 @@
+#include<iostream>
+using namespace std;
+// Note: take a sorted  linked list
+// Lil Buggy Code
+struct node{
+int data;
+struct node*next;
+struct node*prev;
+};
+struct node*newNode(int data){
+struct node*node = new struct node;
+node->data = data;
+node->next = NULL;
+node->prev = NULL;
+return node;
+}
 
+void insertDLL(struct node**head,int data){
+    if(*head==NULL){
+        *head = newNode(data);
+    }
+    else {
+        struct node*temp = newNode(data);
+        temp->next = (*head);
+        (*head)->prev = temp;
+        *head = temp;
+    }
+return;
+}
+void printDLL(struct node*head){
+    while(head!=NULL){
+        cout<<head->data<<" <=> ";
+        head = head->next;
+    }
+cout<<endl;
+}
+
+struct node* linkedListToBST(struct node**root){
+
+if(*root==NULL){
+    return NULL;
+}
+
+struct node*fast = *root;
+struct node*slow = *root;
+struct node*prev;
+
+
+
+while(fast!=NULL){
+    fast = fast->next;
+    if(fast!=NULL)
+        {
+            fast = fast->next;
+            prev = slow;
+            slow = slow->next;
+        }
+    }
+prev->next = NULL;  //Break The links
+slow->prev = NULL ;
+
+struct node* prevPrev = prev->prev;
+prev->prev = NULL;
+prevPrev->next = NULL;
+
+cout<<prev->data<<endl;
+printDLL(*root);
+printDLL(slow);
+
+prev->prev = linkedListToBST(root);
+prev->next = linkedListToBST(&slow);
+return prev;
+}
+
+
+int main(){
+struct node*root = NULL;
+insertDLL(&root,8);
+insertDLL(&root,7);
+insertDLL(&root,6);
+/*insertDLL(&root,5);
+insertDLL(&root,4);
+insertDLL(&root,3);
+insertDLL(&root,2);
+insertDLL(&root,1);*/
+printDLL(root);
+linkedListToBST(&root);
+return 0;
+}

Trees/23. Contruct Tree from Preorder and Inorder Traversals.cpp

@@ -1 +1,64 @@
+#include<iostream>
+using namespace std;
 
+
+//---------------------Binary Search
+int BinarySearch(int *a,int key,int low,int high){
+    while(low<=high){
+    int mid = (low+high)/2;
+    if(a[mid]==key)
+        return mid;
+    else if(a[mid]>key)
+        high = mid-1;
+    else
+        low = mid+1;
+    }
+return -1; //Not found
+}
+
+struct node{
+int data;
+struct node*left;
+struct node*right;
+};
+
+struct node*constructTree(int *pre,int *in,int low,int high,int &pre_index,int n){
+
+if(pre_index>=n)
+    return NULL;
+
+if(low>high){
+    return NULL;
+}
+
+else if(low<=high){
+
+    struct node* node = new struct node;
+    node->data = pre[pre_index];
+    int index_in = BinarySearch(in,pre[pre_index],low,high);
+    pre_index++;
+    node->left = constructTree(pre,in,low,index_in-1,pre_index,n);
+    node->right = constructTree(pre,in,index_in+1,high,pre_index,n);
+    return node;
+    }
+}
+
+
+void printInorder(struct node*root){
+if(root==NULL)
+    return;
+
+printInorder(root->left);
+cout<<root->data<<" ";
+printInorder(root->right);
+
+}
+
+int main(){
+int preorder[] = {6,3,1,4,7,8,9};
+int inorder[] ={1,3,4,6,7,8,9};
+int n = sizeof(inorder)/sizeof(int);
+int pre_index = 0;
+struct node*root = constructTree(preorder,inorder,0,n-1,pre_index,n);
+printInorder(root);
+}

Trees/24. Convert tree into inorder threaded tree.cpp

@@ -0,0 +1,138 @@
+#include<iostream>
+#include<queue>
+using namespace std;
+
+struct node{
+int data;
+struct node*left;
+struct node*right;
+struct node*next;  //Next will point to inorder successor
+};
+
+//---------------------------------------Build Level Order
+struct node*build(){
+struct node*root = new node;
+cout<<"Enter Root's Data";
+cin>>root->data;
+
+queue<node*> q;
+q.push(root);
+
+while(!q.empty()){
+
+    struct node*temp = q.front();
+    q.pop();
+    cout<<"Enter the children (or -1) for node with data as "<<temp->data<<" : ";
+    int data1;
+    int data2;
+    cin>>data1>>data2;
+
+    if(data1!=-1){
+          temp->left  = new node;
+          temp->left->data = data1;
+          temp->left->next = NULL;
+         q.push(temp->left);
+    }
+    else{
+    temp->left = NULL;
+    }
+
+    if(data2!=-1){
+        temp->right = new node;
+        temp->right->data = data2;
+        temp->right->next = NULL;
+        q.push(temp->right);
+    }
+    else{
+    temp->right = NULL;
+    }
+  }
+return root;
+}
+//--------------------------------------------------Print Level Order
+void printLevelOrder(node*root){
+
+queue<node*> q;
+q.push(root);
+q.push(NULL);
+
+while(!q.empty()){
+    node*temp = q.front();
+    q.pop();
+
+    if(q.empty())
+        {
+        cout<<endl;
+        break;
+        }
+
+    else if(temp==NULL)
+    {
+        q.push(NULL);
+        cout<<endl;
+    }
+    else{
+        cout<<temp->data<<" ";
+        if(temp->left!=NULL){
+            q.push(temp->left);
+        }
+        if(temp->right!=NULL){
+            q.push(temp->right);
+        }
+    }
+}
+}
+//---------------------------------------------------Set Next pointers
+void setNextPointers(struct node*root){
+    if(root==NULL)
+    {
+     return;
+    }
+    struct node*temp = root ;
+
+
+    if(root->left!=NULL){
+    root->left->next = root;
+    }
+    setNextPointers(root->left);
+
+    if(root->right!=NULL){
+    root->right->next = root->next;
+    root->next = root->right;
+    }
+    setNextPointers(root->right);
+}
+
+//---------------------------------------------------Print Inorder
+void printInorder(struct node*node){
+if(node==NULL)
+    return;
+printInorder(node->left);
+if(node->next!=NULL)
+    cout<<node->data<<" -> "<<node->next->data<<endl;
+else
+    cout<<node->data<<" -> NULL ";
+printInorder(node->right);
+
+}
+
+void printInorderUsingNextPointers(struct node*root){
+    while(root!=NULL)
+    {
+        cout<<root->data<<" ";
+        root = root->next;
+
+    }
+}
+
+int main(){
+struct node*root1 = build();
+root1->next = NULL;
+setNextPointers(root1);
+
+cout<<"Inorder Recursive with  next fields :"<<endl;
+printInorder(root1);
+cout<<endl<<"Inorder Using Next Pointers (Efficient):"<<endl;
+printInorderUsingNextPointers(root1); // Not it will start from root and it will print only the next larger elements
+cout<<endl;
+}