/*
* August 25, 2015
* The function was written with a few of problems:
*
* Problem 1:
* in the function, only call print function once for root node, and then,
* let recursive function handle the children.
* Ensure that any node is printed once, not more than once.
*
* Problem 2:
* base case: discussion of null pointer, so
* no need to check if child pointer is not null
* if(r.middle !=null) <-- problem 2
*
* problem 3:
* redudant printout of nodes
*
* problem 4:
* too many printout function calls
*
* problem 5:
* recursive function is missing here!
*
* problem 6:
* So, time out! the function was left with a few problems:
*
* Situation/ Task, Action, Result - SAR structure:
* 1. Situation/ Task: under pressure, perform a recursive function
* 2. Action: Use test case to get the idea, and then, write code;
* but, there are a few of problems in recursive function construction
* 3. Result:
* The recursive function with a few of serious bugs
* 1. base case - ok
* 2. recursive function calls are missing
* 3. action - output are duplicated, root node, and also child nodes are outputed in one function
*
* Lessons learned about recursive solution (January 6, 2016):
* 1. Learn how to think using recursive solution
* 2. Always fully use "base case" checking, do not repeat the same checking after base case checking.
* 3. Only take action for root node, and then, let recursive function do the work for its children.
*
* But, remember that recursive solution is the most simple solution to write, short and concise; but
* may not be most efficient, maybe a lot of redundant recursive function calls.
*
*/
public static void preOrderTraversal_Trial(tNode r)
{
if (r == null)
{
return;
}
Console.WriteLine(r.data);
if (r.middle != null) // Problem 2:
{
Console.WriteLine(r.middle.data); // Problem 3
preOrderTraversal_Trial(r.middle);
}
if (r.left != null) // Problem 2:
{
Console.WriteLine(r.left.data); // Problem 3
}
// problem 5
if (r.right != null) // Problem 2:
{
Console.WriteLine(r.right.data); // Problem 3
}
// Problem 5
}
/*
* print the values of the ternary search tree by doing preorder traversal
* January 5, 2016
* C#
*
* Review unfinished code written on August 25, 2015, and then, write a new one.
*
* common problem:
* 1. problem 1:
* in the function, only call print function once.
* Let recursive function handle the children.
* 2. problem 2:
* base case: discussion of null pointer, so
* no need to check if child pointer is not null
* if(r.middle !=null) <-- problem 2
*
*/
public static void preOrderTraversal(tNode r)
{
if (r == null)
{
return;
}
Console.WriteLine(r.data); // fisrt node
preOrderTraversal(r.middle); // Problem 2:
preOrderTraversal(r.left); // Problem 2:
preOrderTraversal(r.right); // Problem 2:
}
static void Main(string[] args)
{
tNode n1 = new tNode(1);
n1.right = new tNode(2);
n1.right.middle = new tNode(2);
n1.right.right = new tNode(3);
tNode.preOrderTraversal(n1);
Console.WriteLine("second test case");
tNode n2 = new tNode(4);
n2.left = new tNode(2);
n2.left.left = new tNode(1);
n2.left.middle = new tNode(2);
n2.left.right = new tNode(3);
n2.right = new tNode(5);
tNode.preOrderTraversal(n2);
}
