chap binary trees figure an example binary tree node is the root nodes and are ' children nodes and together form subtree node has two childrenits left child is the empty tree and its right child is nodes acand are ancestors of nodes deand make up level of the treenode is at level the edges from to to to form path of length nodes dghand are leaves nodes abceand are internal nodes the depth of is the height of this tree is of the path is if there is path from node to node mthen is an ancestor of mand is descendant of thusall nodes in the tree are descendants of the root of the treewhile the root is the ancestor of all nodes the depth of node in the tree is the length of the path from the root of the tree to the height of tree is one more than the depth of the deepest node in the tree all nodes of depth are at level in the tree the root is the only node at level and its depth is leaf node is any node that has two empty children an internal node is any node that has at least one non-empty child figure illustrates the various terms used to identify parts of binary tree figure illustrates an important point regarding the structure of binary trees because all binary tree nodes have two children (one or both of which might be empty)the two binary trees of figure are not the same two restricted forms of binary tree are sufficiently important to warrant special names each node in full binary tree is either ( an internal node with exactly two non-empty children or ( leaf complete binary tree has restricted shape obtained by starting at the root and filling the tree by levels from left to right in the complete binary tree of height dall levels except possibly level - are completely full the bottom level has its nodes filled in from the left side