binarySearchTree (functional approach)

// Binary search tree
// Functions to insert, generate, and count nodes
// Employs a functional approach

var insert = function(value, tree) {
  // First check whether there is a head
  // If not, set value as head
  if (!tree.value) {
    var tree = {
      value: value,
      left: undefined,
      right: undefined
    }
    
    return tree;
    
  } else {
    if (value > tree.value) {
      // If there is no greater value set
      if (!tree.right) {
        tree.right = {
          value: value,
          left: undefined,
          right: undefined
        }
        return tree;
      } else {
        insert(value, tree.right);
        return tree;
      }
    } else if (value < tree.value) {
      if (!tree.left) {
        tree.left = {
          value: value,
          left: undefined,
          right: undefined
        }
      return tree;
      } else {
        return insert(value, tree.left)
      }
    }
  }
}

var genTree = function(array) {
  var binaryTree = {};
  array.forEach(function(elem) {
    binaryTree = insert(elem, binaryTree);
  })
  return binaryTree;
}

var countNodes = function(tree) {
  var treeCount = 1;
  
  if (!tree) {
    return 0;
  }
  
  treeCount += countNodes(tree.left);
  treeCount += countNodes(tree.right);
  
  return treeCount;
}

var countNodesLessEqualVal = function(tree, value) {
  
  if (!tree) {
    return 0;
  }
  
  console.log("tree is: ", tree)
  
  var nodeCount = 0;

  if (value >= tree.value) {
    nodeCount += 1;
    nodeCount += countNodes(tree.left)
    nodeCount += countNodesLessEqualVal(tree.right, value);
  } else {
    nodeCount += countNodesLessEqualVal(tree.left, value);
  }
  
  return nodeCount;
  
}