const stackStart = getNumNodesOnLevel(treeHeight) - 1;

  // Draw the current node

  fill(0, 0, 255);

  textAlign(CENTER, CENTER);

  textSize(10);

  text(index, x, y - 30);

  fill(255);

  circle(x, y, 30);

  const value = data[index];

  if (value == undefined) {

    fill(255, 0, 0);

    circle(x, y, 30);

  } else {

    const button = createButton(value.toString());

    button.position(x - button.width/2, y - button.height/2);

    button.mousePressed(() => changeValue(index));

    button.class('unstyled-button');

    buttons.push(button)

​

//       fill(0);

//       textSize(15);

//       text(value, x, y);

    if (index >= stackStart) {

      fill(255, 0, 255);

      textSize(10);

      text(index - stackStart, x, y + 30);

    }

  }

​

  // Base case

  if (height <= 1) return;

​

  // Calculate the positions of child nodes

  const leftX = x - branchLength;

  const rightX = x + branchLength;

  const nextY = y + 100;

​

  // Draw lines to connect the current node to its child nodes

  line(x, y + 15, leftX, nextY - 15);

  line(x, y + 15, rightX, nextY - 15);

​

  // Recursively draw the left and right subtrees

  drawBinaryTree(leftX, nextY, height - 1, branchLength / 2, getLeftChildIndex(index));

  drawBinaryTree(rightX, nextY, height - 1, branchLength / 2, getRightChildIndex(index));

}

​

function getLeftChildIndex(i) {

  return 2 * i + 1;

}

​

function getRightChildIndex(i) {

  return 2 * i + 2;

}

​

function isValidNumberSequence(raw) {

  // Remove spaces from the input string

  const sanitizedInput = raw.replace(/\s/g, '');

​

  // Check if the sanitized input is a sequence of numbers separated by commas

  const isValid = /^[0-9]+(,[0-9]+)*$/.test(sanitizedInput);

​

  return isValid;

}

​

function convertStringToArray(raw) {

  // Remove spaces from the input string

  const sanitizedInput = raw.replace(/\s/g, '');

​

  // Split the sanitized input into an array using commas as the delimiter

  const numberArray = sanitizedInput.split(',');

​

  // Convert each element of the array to a number

  const resultArray = numberArray.map(Number);

​

  return resultArray;

}

​

function isStringInteger(raw) {

  // Use parseInt to attempt to convert the string to an integer

  let num = parseInt(raw, 10);

​

  // Check if the parsed value is a valid number and if it's equal to the original string

  return !isNaN(num) && num.toString() === raw;

}

​

function watchWarning(selector, isError) {

  const warningElement = select(selector);

  warningElement.style('display', 'none');

  if (isError) {

    warningElement.style('display', 'block');

  }

  return isError; // return true if has errors

}

​

function changeValue(index) {

  const raw = window.prompt("Enter new value:");

  if (!raw) return;

  if (!isStringInteger(raw)) {

    window.alert("Invalid input!");

    return;

  }

  data[index] = parseInt(raw);

  const dataInput = select("#heapData");

  dataInput.value(data.toString());

  const eventObj = {target: {value: data.toString()}}

  updateData(eventObj);

}