Count Visible Nodes in Binary Tree

binary_tree_problem.js

// Question: In a binary tree, if in the path from root to the node A, there is no node with greater value than A’s, this node A is visible.
// We need to count the number of visible nodes in a binary tree.
// For example, in the following tree:
//
//         5
//      /     \
//    3        10
//   /  \     /
// 20   21   1
//
// There are four (4) visible nodes: 5, 20, 21, and 10.

function solution(T) {
  return traverseTree(-1, -1, T);
}

function traverseTree(nVisibleNodes, parentNodeValue, node) {
  let n = 0;
  if (node.x > parentNodeValue) nVisibleNodes += 1;
  if (null !== node.l) n += traverseTree(nVisibleNodes, node.x, node.l);
  if (null !== node.r) n += traverseTree(nVisibleNodes, node.x, node.r);
  nVisibleNodes += n;
  return nVisibleNodes;
}

const binaryTree = {
  x: 5,
  l: {
    x: 3,
    l: {
      x: 20,
      l: null,
      r: null,
    },
    r: {
      x: 21,
      l: null,
      r: null,
    },
  },
  r: {
    x: 10,
    l: {
      x: 1,
      l: null,
      r: null,
    },
    r: null,
  },
};

solution(binaryTree);

Hi Justin,
please try for this inputs:
[3,1,4,3, null,1,5] expected:4 but showing 5
[3,3,null,4,2] expected: 3 but sowing 1
[1] expected: 1 but showing 0
not working