Homework-1/qsort.py

30 lines
686 B
Python

def qsort(xs):
if xs == []: return []
pivot = xs[0]
left = [x for x in xs if x < pivot]
right = [x for x in xs[1:] if x >= pivot]
return [qsort(left)] + [pivot] + [qsort(right)]
def sorted(tree):
if tree == []: return []
return sorted(tree[0]) + [tree[1]] + sorted(tree[2])
def search(tree, x):
return _sorted(tree, x) != []
def insert(tree, x):
node = _sorted(tree, x)
if node == []:
node.append([])
node.append(x)
node.append([])
def _sorted(tree, i):
if tree == []: return tree
pivot = tree[1]
if pivot == i: return tree
elif i < pivot: return _sorted(tree[0], i)
else: return _sorted(tree[2], i)