Solving Programming Problems

To finish off my Java Algorithm tutorial, I thought it would be interesting to cover solving programming problems in general. So, in this tutorial I’ll answer the question I’ve been getting, which is how to print a tree data structure.

On our journey to better understand how to solve problems I will first solve the basic problem. Then in the next part of the tutorial I will perfect printing any type of tree. The code below will better explain the process of solving this problem.

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Code From the Video

4 ROW TREE

_______1
___1_______1
_1___1___1___1
1_1_1_1_1_1_1_1

1st Row Indent 7 Spaces 0
2nd Row Indent 3 Spaces 7
3rd Row Indent 1 Spaces 3
4th Row Indent 0 Spaces 1

Indent : -2^-n * (-16+2^n) start with 1
Spaces : 0 and then whatever Indent was

First Index Per Row
0
1 2
3 4 5 6
7 8 9 10 11 12 13 14
.5 * (-2 + (Math.pow(2, iteration)))

Items Per Row
1, 2, 4, 8
Math.pow(2, iteration - 1)

Max Index Per Row
indexToPrint + itemsPerRow

Indent Number
Indent Number Space Number
Indent Number Space Number Space...

I need 1 index followed by multiple numbers & spaces every time

public void printTree(int rows) {

		int spaces = 0;

		int iteration = 1;

		while (iteration <= rows) {

			int indent = (int) Math
					.abs(((Math.pow(-2, -iteration)) * (-16 + (Math.pow(2,
							iteration)))));

			int indexToPrint = (int) (.5 * (-2 + (Math.pow(2, iteration))));

			int itemsPerRow = (int) (Math.pow(2, iteration - 1));

			int maxIndexToPrint = indexToPrint + itemsPerRow;

			for (int j = 0; j < indent; j++)
				System.out.print(" ");

			for (int l = indexToPrint; l < maxIndexToPrint; l++) {

				System.out.print(theHeap[l].key);

				for (int k = 0; k < spaces; k++)
					System.out.print(" ");

			}

			spaces = indent;

			iteration++;

			System.out.println();

		}

	}