Binary Search Tree using C++

#include<iostream.h>
#include<conio.h>
#include<stdlib.h>
int flag=0;
int l=0,r=0;

typedef struct node  {
    struct node *left;
    int val;
    struct node *right;
}tree;

tree *root,*t,*temp,*max;

tree *insert(tree *t,int k) {

   if(flag==0) {
      root=new tree;
      root->val=k;
      root->left=NULL;
      root->right=NULL;
      flag=1;
   }
   else {
       if(t==NULL) {
         t=new tree;
         t->val=k;
         t->left=NULL;
         t->right=NULL;
       }
       else if(k==t->val)
              cout<<"Already present..\n";
       else if(k>t->val)
              t->right=insert(t->right,k);
       else
              t->left=insert(t->left,k);
   }
   return t;
}


void inorder(tree *t) {
      if(t->left!=NULL)
         inorder(t->left);
      cout<<t->val<<" ";
      if(t->right!=NULL)
         inorder(t->right);
}

void preorder(tree *t) {
     cout<<t->val<<" ";
     if(t->left!=NULL)
          preorder(t->left);
     if(t->right!=NULL)
          preorder(t->right);
}

void postorder(tree *t) {
     if(t->left!=NULL)
        postorder(t->left);
     if(t->right!=NULL)
        postorder(t->right);
     cout<<t->val<<" ";
}

int height(tree *t)  {
  if(t->left!=NULL) {
       l++;
       height(t->left);
  }
  if(t->right!=NULL) {
       r++;
       height(t->right);
  }
  return (l>r?l:r)
}

void mirror(tree *t) {
     if(t==NULL)
         return;
     mirror(t->left);
     mirror(t->right);
     temp=t->left;
     t->left=t->right;
     t->right=temp;
}

void findmax(tree *t) {
  /*for normal binary trees*/
  if(t) {
     if(t->val > max->val)
        max=t;
     findmax(t->left);
     findmax(t->right);
  }
}

void main() {
   clrscr();
   int k=0;
   do {
       cout<<"Enter value:";
       cin>>k;
       if(k)
          t=insert(root,k);
   }while(k!=0);

   cout<<"Preorder:";
   preorder(root);
   cout<<"\nInorder:";
   inorder(root);
   cout<<"\nPostorder:";
   postorder(root);
   cout<<"\nHeight:"<<height(root);
   cout<<"\nBalance factor : "<<(abs(l-r));
   mirror(root);
   cout<<"\nMirror tree:";
   inorder(root);
   max=root;
   findmax(root);
   cout<<"\nMax value : "<<max->val;
   getch();
}

Stack using C++

#include<iostream.h>
#include<conio.h>
#include<dos.h>

int a[10],top=-1,size=5;

void push()
{
  int k;
  cout<<"\nEnter element :";
  cin>>k;
  top++;

  if(top>=size)
   cout<<"\nStack overflow..\n";
  else
   a[top]=k;
}

void pop()
{
  if(top>=0)
  {
    cout<<"\n"<<a[top]<<endl;
    top--;
  }
  else
    cout<<"\nStack underflow..\n";
  getch();
}

void print()
{
  for(int i=top;i>=0;i--)
   cout<<a[i]<<"\n";
  getch();
}


void main()
{
  int ch;
y:
  clrscr();
  cout<<"\n1.Push\n2.Pop\n3.Print\n4.Exit\n\nEnter ur choice : ";
  cin>>ch;
  if(ch==1)
  {
    push();
    goto y;
  }
  else if(ch==2)
  {
    pop();
    goto y;
  }
  else if(ch==3)
  {
    print();
    goto y;
  }
  else if(ch==4)
  {
    goto x;
  }
  else
  {
    cout<<"\nInvalid choice..\n";
    goto y;
  }

x:
  getch();
}

Data Structures Interview Questions and Answers

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