Difference between revisions of "99 questions/Solutions/61"

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Revision as of 00:06, 14 July 2010

Count the leaves of a binary tree

A leaf is a node with no successors. Write a predicate count_leaves/2 to count them.

count_leaves  Empty                 = 0
count_leaves (Branch a Empty Empty) = 1
count_leaves (Branch a left  right) = count_leaves left + count_leaves right