Which tree traversal in C requires the use of a queue?

Do you have any idea what makes minimum spanning trees so special? The c language is taken for granted.

Note:  The STL (Standard Template Library) stack and queue classes - not Nyhoff's - must be used for this assignment. Write a program that queries the user for a string of characters, placing the characters on both a stack and a queue.  Then use basic stack and queue operations to determine if the string is a palindrome and report the result.

Implement the pre-order tree traversal algorithm in C++. This program should use the following binary tree (see image) and display the pre-order tree traversal of the nodes’ values. Feel free to write this iteratively or recursively. Also, explain how it works and how a new tree could be provided to the code. PS: make sure that the logic of the program is correct, meaning that it can work well with different binary trees. I would like to change the tree input to the pre-order traversal function. The program should work errorless and display the result correctly. No need to code it to read the user input, however, provide instructions on how a new tree can be defined in this program to check if the program works fine with different trees.