kthSmallest InterviewPrepPrompt

kthSmallest

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @param {number} k
 * @return {number}
 */

//VERSION 1 OF THE SOLUTION
/*
var kthSmallest = function(root, k) {
    //input = root tree node, target num
    //output = target num if found
    
    //check if root is the target value
    if(root.val === k) {
      return root.val
    }
    
    //results container
    let result = null;
    
    //helper function
    function checkNode(node, target) {
      if(node.val === k) {
        result = node.val
        return;
      } else if(node.right) {
        return checkNode(node.rigth);
      } else {
        return checkNode(node.left);
      }
    }
    
    checkNode(root);
    
    return result;
};
*/

//VERSION 2 OF THE SOLUTION
var kthSmallest = function(root, k) {
    //input = root tree node, target num
    //output = target num if found

    //results container
    let result = null;
    
    //helper function
    function checkNode(node, target) {
        
      if(node.val === target) {
        result = node.val
        return;
      }

      if (node.right !== null) {
        checkNode(node.right, target);
      } 

      if (node.left !== null) {
        checkNode(node.left, target);
      }

    }
    
    checkNode(root, k);
    
    return result;
};