Update treeBasics

Author: prpratheek

treeBasics

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+1) The maximum number of nodes at level ‘l’ of a binary tree is 2^l-1.
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+3) In a Binary Tree with N nodes, minimum possible height or minimum number of levels is  ? Log2(N+1) 
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+4) A Binary Tree with L leaves has at least   ? Log2L ? + 1   levels
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+Full Binary Tree A Binary Tree is full if every node has 0 or 2 children.
+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
+Perfect Binary Tree A Binary tree is Perfect Binary Tree in which all internal nodes have two children and all leaves are at the same level.
+A degenerate (or pathological) tree A Tree where every internal node has one child. Such trees are performance-wise same as linked list.
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+Note that nodes are unlabeled. If the nodes are labeled, we get more number of trees. We can find the number of binary tree by Catalan number number: Here n = 3 Number of binary tree = (2nCn)/ n+1 = (2*3C3)/ 4+1 = 5. So, option (B) is correct.