CODE EXAMPLE FOR PYTHON

depth first

class Node {
  constructor(data) {
    this.left = null;
    this.right = null;
    this.data = data;
  }
}

// depth first search tree traversal using recursive
//static implementation
const depthFirstTraversal = (root) => {
  if (root === null) return [];
  const leftValues = depthFirstTraversal(root.left); //[2 , 4 , 5 ]
  const rightValues = depthFirstTraversal(root.right); // [3 , 6 , 7 ]
  return [root.data, ...leftValues, ...rightValues];
};
const one = new Node(1);
const two = new Node(2);
const three = new Node(3);
const four = new Node(4);
const five = new Node(5);
const six = new Node(6);
const seven = new Node(7);

one.left = two;
one.right = three;
two.left = four;
two.right = five;
three.left = six;
three.right = seven;
// console.log(depthFirstTraversal(one)); // [1 ,2 , 4 , 5  ,3 , 6 ,7]

// depth first search tree traversal using while loop :

const depthFirstTraversal2 = (root) => {
  if (root === null) return [];

  const result = [];
  const stack = [root];

  while (stack.length > 0) {
    const current = stack.pop();
    result.push(current.data);
    if (current.right) stack.push(current.right);
    if (current.left) stack.push(current.left);
  }
  return result;
};
console.log(depthFirstTraversal2(one)); // [1 ,2 , 4 , 5  ,3 , 6 ,7]