binarysearchtree.py

def pprint(d, level=0):
    value = d.get('value', None)
    left = d.get('left', None)
    right = d.get('right', None)
    if value is not None:
        print('%s%s' % (' ' * level, value))
    if left is not None:
        pprint(left, level+4)
    if right is not None:
        pprint(right, level+4)
from pprint import pprint

def node(value, left=None, right=None):
    d = {'value': value}
    if left is not None:
        d['left'] = left
    if right is not None:
        d['right'] = right
    return d

def from_sorted(l, start, end):
    middle = (start + end) / 2 
    print(start, middle, end)
    if start == middle:
        return node(l[middle])
    return node(l[middle], from_sorted(l, start, middle), from_sorted(l, middle, end))

def build_tree(l):
    if len(l) == 0:
        return {}
    return from_sorted(l, 0, len(l))
pprint(build_tree([1,2]))