#include <bits/stdc++.h>
using namespace std;

class Node{
  public:
  int data;
  Node *left,*right;
  Node(int val){
    data=val;
    left=right=NULL;
  }
};

class Btree{
  public:
  Node *root;
  int max_sum_from_root_to_leaf=0,diameter=0;
  std::vector<Node*> v;
  std::vector<Node*> L;
  std::vector<Node*> R;
  std::map<int, Node*> mpt;
  std::map<int, Node*> mpb;
  Btree(){
    root=NULL;
  }
  void preorder(Node *root){
    Node *temp=root;
    if(temp==NULL)
    return;
    cout<<temp->data<<" ";
    preorder(temp->left);
    preorder(temp->right);
  }
  
  void postorder(Node *root){
    Node *temp=root;
    if(temp==NULL)
    return;
    postorder(temp->left);
    postorder(temp->right);
    cout<<temp->data<<" ";
  }
  
  void inorder(Node *root){
    Node *temp=root;
    if(temp==NULL)
    return;
    inorder(temp->left);
    cout<<temp->data<<" ";
    inorder(temp->right);
  }
  
  void levelorder(Node* root){
    queue<Node*> q;
    q.push(root);
    int k=0;
    while(!q.empty()){
      int count=q.size(),sum=0;
      for(int i=0;i<count;i++){
      Node *t=q.front();
      cout<<t->data<<" ";sum+=t->data;
      q.pop();
      if(t->left)
      q.push(t->left);
      if(t->right)
      q.push(t->right);
      }
      cout<<"---> sum of level "<<++k<<" = "<<sum<<endl;
    }
  }
  
  int height(Node* root){
    if(root==NULL)
      return 0;
    int lh=height(root->left);
    int rh=height(root->right);
    diameter=max(diameter,lh+rh);
    return max(lh,rh)+1;
  }
  
  int getDiameter(Node* root){
    diameter=0;
    height(root);
    return diameter;
  }
  
  void sumPath(Node* root,int sum=0){
    if(root==NULL)
    return;
    if(root->left==NULL && root->right==NULL){
      sum+=root->data;
      max_sum_from_root_to_leaf=max(sum,max_sum_from_root_to_leaf);
      return;
    }
    sumPath(root->left,sum+root->data);
    sumPath(root->right,sum+root->data);
  }
  
  void Lview(Node* root){
    queue<Node*> q;
    q.push(root);
    while(!q.empty()){
      int count=q.size();
      L.push_back(q.front());
      for(int i=0;i<count;i++){
      Node *t=q.front();
      q.pop();
      if(t->left)
      q.push(t->left);
      if(t->right)
      q.push(t->right);
      }
    }
  }
  
  void Rview(Node* root){
    queue<Node*> q;
    q.push(root);
    while(!q.empty()){
      int count=q.size();
      R.push_back(q.back());
      for(int i=0;i<count;i++){
      Node *t=q.front();
      q.pop();
      if(t->left)
      q.push(t->left);
      if(t->right)
      q.push(t->right);
      }
    }
  }
  
  void Tview(Node* root,int hd){
    /*
    vector<Node*> T(L);
    reverse(T.begin(),T.end());
    for(auto it=R.begin()+1;it!=R.end();++it)
    T.push_back(*it);
    for(auto x:T)
    cout<<x->data<<" ";
    */
    if(root==NULL)
    return;
    
    if(!mpt.count(hd))
    mpt[hd]=root;
    
    Tview(root->left,hd-1);
    Tview(root->right,hd+1);
  }
  
  void Bview(Node *root,int hd){
    if(root==NULL)
    return;
    
    mpb[hd]=root;
    
    Bview(root->left,hd-1);
    Bview(root->right,hd+1);
  }
  
  void spiral(Node *root){
    queue<Node*> q;
    vector<Node*> sp;
    q.push(root);
    int level=0;
    while(!q.empty()){
      int count=q.size(),sum=0;
      for(int i=0;i<count;i++){
      Node *t=q.front();
      sp.push_back(t);
      q.pop();
      if(t->left)
      q.push(t->left);
      if(t->right)
      q.push(t->right);
      }
      level++;
      if(level & 1)
      reverse(sp.begin(),sp.end());
      for(auto x:sp)
      cout<<x->data<<" ";
      sp.clear();
    }
  }
  
  bool search(Node *root,int val){
    if(root==NULL)
    return 0;
    bool ltree=search(root->left,val);
    bool rtree=search(root->right,val);
    return (root->data==val) or ltree or rtree;
  }
};

int main() 
{
    Btree t;
    t.root=new Node(10);
    t.root->left=new Node(20);
    t.root->right=new Node(30);
    t.root->left->left=new Node(40);
    t.root->left->right=new Node(50);
    t.root->right->left=new Node(60);
    t.root->right->right=new Node(70);
    cout<<"Preorder: ";
    t.preorder(t.root);
    cout<<endl<<"Inorder: ";
    t.inorder(t.root);
    cout<<endl<<"Postorder: ";
    t.postorder(t.root);
    cout<<endl<<"Levelorder :"<<endl;
    t.levelorder(t.root);
    cout<<"Height of Btree = "<<t.height(t.root)<<endl;
    cout<<"Diameter of Btree = "<<t.getDiameter(t.root)<<endl;
    t.sumPath(t.root);
    cout<<"max_sum_from_root_to_leaf = "<<t.max_sum_from_root_to_leaf<<endl;
    cout<<"Left view of Btree : ";
    t.Lview(t.root);
    for(auto x:t.L)
    cout<<x->data<<" ";
    cout<<endl;
    cout<<"Right view of Btree : ";
    t.Rview(t.root);
    for(auto x:t.R)
    cout<<x->data<<" ";
    cout<<endl;
    cout<<"Top view of Btree : ";
    t.Tview(t.root,0);
    for(auto x:t.mpt)
    cout<<x.second->data<<" ";
    cout<<endl;
    cout<<"Bottom view of Btree : ";
    t.Bview(t.root,0);
    for(auto x:t.mpb)
    cout<<x.second->data<<" ";
    cout<<endl;
    cout<<"Elements in spiral order : ";
    t.spiral(t.root);
    cout<<endl;
    if(t.search(t.root,33))
    cout<<"Present";
    else
    cout<<"Absent";
    return 0;
} 
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Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
} 

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
} 

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}  

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition); 

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}