what is a complete binary tree
Complete Binary Tree: A Binary Tree is complete Binary Tree if all levels are completely filled except possibly the last level and the last level has all keys as left as possible
Following are examples of Complete Binary Trees
18
/ \
15 30
/ \ / \
40 50 100 40
18
/ \
15 30
/ \ / \
40 50 100 40
/ \ /
8 7 9
Practical example of Complete Binary Tree is Binary Heap.