Task: traverse a tree of objects (each object has fields value and elements) and calculate the sum of all values. How would you implement this?

To traverse a tree of objects with fields value and elements (where elements is an array of child objects) and calculate the sum of all values, you can use a recursive function.

Example in JavaScript:

function sumValues(node) {
  let sum = node.value;
  if (node.elements && node.elements.length > 0) {
    for (const child of node.elements) {
      sum += sumValues(child);
    }
  }
  return sum;
}

// Example usage:
const tree = {
  value: 10,
  elements: [
    { value: 5, elements: [] },
    { value: 3, elements: [
      { value: 2, elements: [] }
    ]}
  ]
};

console.log(sumValues(tree)); // 20

The sumValues function takes a node, adds its value to the sum, then recursively calls itself for all child elements, accumulating the total sum.