Tree Components

In the tree structure below, each circle that contains a value is called a node.

The first node from where the tree originates is called the root node.

The tree creates a hierarchical structure where except for the root node, every other node has a parent and zero or more children.

The nodes with no children are called leaves.

Exercise Given the tree structure above, complete the table below:

Answer
The root is
The leaves are
The parent of node with value $21$ is
The children of node with value $5$ are
Solution
Answer
The root is$9$
The leaves are$4, 8, 14, 20, 25$
The parent of node with value $21$ is$17$
The children of node with value $5$ are$2, 7$

The nodes which belong to the same "parent" are called siblings!

The parent-child relationship between nodes can be extended to ancestors and descendants.

For example,

  • The nodes $21$, $17$, and $9$ are ancestors of $25$.
  • The nodes $2$, $7$, $4$, and $8$ are descendants of $5$.

The root is an ancestor of every node in a tree, and every node is a descendant of the root.

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