Tidy tree drawing Algorithm

The algorith follows three aesthtic rules that are to be considered while tree drawing. In a first post-order walk, every node of the tree is assigned a preliminary x-coordinate(held in a field of x). In addition, internal nodes are given modifier's which will later be used used to movetheir sons right. During a second pre-order walk, each node is a given a final x-coordinate by summing its preliminary x-coordinate and the modifier's of all the node's ancestors. The y-coordinate depends, as before, on the height of the node.

• The first aesthetic

states that the nodes that are on the same level(i.e have the same height) should be in a straight line, and the lines defining the levels should be parallel.

• The second aesthetic

states, that in a binary tree, a left son should be posi-tioned left of its father and each right son right of its father.

• The third aesthetic

states that a parent should be centered over its children.

Variables used :

Variables used inside the Structure(tree)

• left_son : INTEGER

It accepts to values 0 and 1.True(=1) means left son exists for the given node else False(=0)

• right_son : INTEGER

It accepts to values 0 and 1.True(=1) means left son exists for the given node else False(=0)

• left_son_index : INTEGER

The index of the left child of the current node

• right_son_index : INTEGER

The index of the right child of the current node

• modifier_t : INTEGER

Used to calculate the value of x

• height : INTEGER

Gives the height of the node

• x : INTEGER

The x value of node as calculated

• y : INTEGER

The y value of node as calculated

• father : INTEGER

The index value of father

• status : INTEGER

The status value of node as calculated/assigned

• end : INTEGER

The variable useful for break condition

An example case

Right side is the terminal where you input the details, the output is seen in the left side window