ramyaDhanush / Tree

To hold basics and advanced concepts in tree data structure with problems that can be solved using tree

Tree

To hold basics and advanced concepts in tree data structure with problems that can be solved using tree 0. FULL BINARY TREE / STRICTLY BINARY TREE Every node must have two children, except the leaf nodes.

1. INCOMPLETE BINARY TREE / ALMOST COMPLETE BINARY TREE Every node must have two children's in all levels except second last level and should be filled from left to right.
2. COMPLETE BINARY TREE / PERFECT BINARY TREE Every node must have two children's in all the levels (Each level there should be 2^L where L is level)
3. LEFT SKEWED BINARY TREE Every node should have only left children.
4. RIGHT SKEWED BINARY TREE Every node should have only right children.

LinkedList Representation

// **Tree using LinkedList**

#include <iostream>
using namespace std;

struct Node {
  int data;
  Node *left, *right;
  Node(int data): data{data}, left{nullptr}, right{nullptr}{}
};


void print_dfs(Node* root){
  if(root == nullptr) return;

  cout<<root->data<<" ";
  print_bfs(root->left);
  print_bfs(root->right);
}

int main(){
  Node *root = new Node(1);
  Node *left = new Node(2);
  Node *right = new Node(3);
  Node *left_left = new Node(4);
  Node *left_right = new Node(5);
  Node *right_left = new Node(6);
  Node *right_right = new Node(7);

  root->left = left;
  root->right = right;

  left->left = left_left;
  left->right = left_right;

  right->left = right_left;
  right->right = right_right;


  // Print DFS
  print_dfs(root);
}

Array Representation

If parent is p and array starts from 0 to n-1 then left child = (2p)+1 right child = (2p)+2

Array starts from 1 to n then left child = (2p) right child = (2p)+1

#include <iostream>
using namespace std;

char tree[10];

void root(char key){
  if(tree[1] != '\0'){
    cout<<"Tree Already have root";
  }
  else tree[1] = key;
}

void set_left(char key, int parent){
  if(tree[parent] == '\0'){
    cout<<"Can't set child at"<<(parent*2) + 1<<" , no parent found";
  }
  else tree[parent * 2] = key;
}

void set_right(char key, int parent){
  if(tree[parent] == '\0'){
    cout<<"Can't set child at"<<(parent*2) + 2<<" , no parent found";
  }
  else tree[(parent * 2) + 1] = key;
}

void print_tree(){
  for(int i=1; i<10; i++){
    if(tree[i] != '\0') cout<<tree[i]<<" ";
    else cout<<" null " ;
  }
}

int main(){
  root('A');
  set_left('B', 1);
  set_right('C', 1);
  set_left('D', 2);
  set_right('E', 2);
  set_left('F', 3);
  set_right('G', 3);
  print_tree();
}

Height of a binary tree