Difference between revisions of "99 questions/Solutions/61"
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<haskell> |
<haskell> |
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| − | countLeaves |
+ | countLeaves Empty = 0 |
| − | countLeaves (Branch |
+ | countLeaves (Branch _ Empty Empty) = 1 |
| − | countLeaves (Branch |
+ | countLeaves (Branch _ Empty r) = countLeaves r |
| + | countLeaves (Branch _ l Empty) = countLeaves l |
||
| + | countLeaves (Branch _ l r) = countLeaves l + countLeaves r |
||
</haskell> |
</haskell> |
||
Revision as of 20:13, 20 January 2011
Count the leaves of a binary tree
A leaf is a node with no successors. Write a predicate count_leaves/2 to count them.
countLeaves Empty = 0
countLeaves (Branch _ Empty Empty) = 1
countLeaves (Branch _ Empty r) = countLeaves r
countLeaves (Branch _ l Empty) = countLeaves l
countLeaves (Branch _ l r) = countLeaves l + countLeaves r