tree exercise

tree.js

function traverse(node, callback) {
  if (node !== null) {
    traverse(node.l, callback);
    callback(node.x)
    traverse(node.r, callback);
  }
}

function solution(T) {
  const visibles = [];
  traverse(T, x => {
    if (x >= T.x) {
      visibles.push(x);
    }
  })

  return visibles;
}

const T = {
  x: 8,
  l: {
    x: 2,
    l: {
      x: 8,
      l: null,
      r: null
    },
    r: null
  },
  r: {
    x: 5,
    l: null,
    r: null
  }
};

console.log(solution(T));