99 problems - python - 57

Binary search trees (dictionaries)

Use the predicate add/3, developed in chapter 4 of the course, to write a predicate to construct a binary search tree from a list of integer numbers.

# Example:

# * construct([3,2,5,7,1],T).
# T = t(3, t(2, t(1, nil, nil), nil), t(5, nil, t(7, nil, nil)))

# Then use this predicate to test the solution of the problem P56.

# Example:

# * test-symmetric([5,3,18,1,4,12,21]).
# Yes
# * test-symmetric([3,2,5,7,1]).
# No
def construct(nums):
    if not nums:
        return None
    ordered_nums = sorted(nums)
    center_index = (len(nums) / 2) 
    return (ordered_nums[center_index], construct(ordered_nums[:center_index]), construct(ordered_nums[center_index+1:]))

def test_symmetric(nums):
    return symmetric_binary_tree(construct(nums))