def convert_sorted_array_to_bst(array, l, h):
if l > h:
return None
mid = (l + h) // 2
root = Node(array[mid])
root.left = convert_sorted_array_to_bst(array, l, mid - 1)
root.right = convert_sorted_array_to_bst(array, mid + 1, h)
return root
def convert(preorder, inorder, start, end):
global pre_index
if start > end:
return None
root_val = preorder[pre_index]
pre_index += 1
root = Node(root_val)
in_index = search(root_val, inorder, start, end)
root.left = convert(preorder, inorder, start, in_index - 1)
root.right = convert(preorder, inorder, in_index + 1, end)
return root
def create_tree(post_order, _min, _max):
global POST_INDEX
if POST_INDEX < 0:
return None
root = None
key = post_order[POST_INDEX]
if _min < key < _max:
root = Node(key)
POST_INDEX -= 1
root.right = create_tree(post_order, key, _max)
root.left = create_tree(post_order, _min, key)
return root
def create_tree(pre, pre_ln):
global index
if index >= len(pre):
return None
root = Node(pre[index])
if pre_ln[index] == 'L':
index += 1
return root
index += 1
root.left = create_tree(pre, pre_ln)
root.right = create_tree(pre, pre_ln)
return root
def create_bst(pre_order, _min, _max):
global PRE_INDEX
if PRE_INDEX >= len(pre_order):
return None
root = None
data = pre_order[PRE_INDEX]
if _min < data < _max:
root = Node(data)
PRE_INDEX += 1
root.left = create_bst(pre_order, _min, data)
root.right = create_bst(pre_order, data, _max)
return root
def construct_tree(pre, post, start, end, N):
global PRE_INDEX
if PRE_INDEX >= N or start > end:
return None
root = Node(pre[PRE_INDEX])
PRE_INDEX += 1
if start == end:
return root
index = search(post, pre[PRE_INDEX], start, end)
if index <= end:
root.left = construct_tree(pre, post, start, index, N)
root.right = construct_tree(pre, post, index + 1, end, N)
return root
def get_test_tree():
root = Node('a')
root.left = Node('b')
root.right = Node('c')
root.left.left = Node('d')
root.left.right = Node('e')
root.right.left = Node('f')
root.right.right = Node('g')
root.left.left.left = Node('h')
root.left.left.right = Node('i')
root.left.right.left = Node('j')
root.left.right.right = Node('k')
root.right.left.left = Node('l')
root.right.left.right = Node('m')
root.right.right.left = Node('n')
root.right.right.right = Node('o')
return root
def build_tree(arr, start, end):
if start > end:
return
root_index = find_max_index(arr, start, end)
root = Node(arr[root_index])
root.left = build_tree(arr, start, root_index - 1)
root.right = build_tree(arr, root_index + 1, end)
return root
# r = build_tree([1, 5, 10, 40, 30, 15, 28, 20], 0, 7)
# print r
# print r.left
# print r.right
# print r.left.left
# print r.right.right
# print r.left.left.left
# print r.right.right.left
# print r.right.right.right
def get_all_trees(arr, start, end):
if start > end:
return [None]
trees = []
for i in range(start, end + 1):
l_trees = get_all_trees(arr, start, i - 1)
r_trees = get_all_trees(arr, i + 1, end)
for j in l_trees:
for k in r_trees:
node = Node(arr[i])
node.left = j
node.right = k
trees.append(node)
return trees
left_tail.right = root
root.left = left_tail
head = left_head
if right_head:
root.right = right_head
right_head.left = root
tail = right_tail
return head, tail
if __name__ == '__main__':
r = Node(10)
r.left = Node(12)
r.right = Node(15)
r.left.left = Node(25)
r.left.right = Node(30)
r.right.left = Node(36)
ll_head, ll_tail = bt_to_dll(r)
iterator = ll_head
while iterator:
print iterator,
iterator = iterator.right
"""
http://www.geeksforgeeks.org/convert-a-binary-tree-to-a-circular-doubly-link-list/
To do this, just connect head and tail from the above
"""
# set this to none or in the next iteration it gets
# pushed to s2 again
root2 = None
else:
s2.pop()
root2 = root2.right
root1 = None
else:
break
if __name__ == '__main__':
r1 = Node(5)
r1.left = Node(1)
r1.right = Node(10)
r1.left.left = Node(0)
r1.left.right = Node(4)
r1.right.left = Node(7)
r1.right.left.right = Node(9)
r2 = Node(10)
r2.left = Node(7)
r2.right = Node(20)
r2.left.left = Node(4)
r2.left.right = Node(9)
print_common_nodes(r1, r2)
amzn, msft
http://www.geeksforgeeks.org/diameter-of-a-binary-tree/
diameter is also the longest path between two nodes in a tree
"""
from G4G.Problems.bst.vertical_sum import Node
def calculate_diameter(root):
if root is None:
return 0, 0
left_diameter, left_height = calculate_diameter(root.left)
right_diameter, right_height = calculate_diameter(root.right)
height = 1 + max(left_height, right_height)
diameter = max(left_diameter, right_diameter, 1 + left_height + right_height)
return diameter, height
if __name__ == '__main__':
root = Node(1)
root.left = Node(2)
root.right = Node(5)
root.left.left = Node(3)
root.left.right = Node(4)
print calculate_diameter(root)
if is_leaf(root):
return root.data
left_sum = max_leaf_to_root_paths(root.left)
right_sum = max_leaf_to_root_paths(root.right)
curr_sum = left_sum + right_sum + root.data
if curr_sum > MAX_SUM:
MAX_SUM = curr_sum
return max(left_sum, right_sum) + root.data
if __name__ == '__main__':
r = Node(-15)
r.left = Node(5)
r.right = Node(6)
r.left.left = Node(-8)
r.left.right = Node(-1)
r.left.left.left = Node(2)
r.left.left.right = Node(6)
r.right.left = Node(3)
r.right.right = Node(9)
r.right.right.right = Node(0)
r.right.right.right.left = Node(4)
r.right.right.right.right = Node(-1)
r.right.right.right.right.left = Node(10)
max_leaf_to_root_paths(r)
print MAX_SUM
done1 = False
else:
print val2,
done2 = False
if val1 is None and val2 is None:
break
if val1 is None:
print val2,
done2 = False
if val2 is None:
print val1,
done1 = False
if __name__ == '__main__':
r1 = Node(3)
r1.left = Node(1)
r1.left.left = Node(0)
r1.left.right = Node(2)
r1.right = Node(5)
r2 = Node(4)
r2.left = Node(2)
r2.right = Node(6)
r2.right.right = Node(7)
print_merged(r1, r2)
l = root.left.data if root.left else 0
r = root.right.data if root.right else 0
if l + r == root.data:
return is_child_sum_met(root.left) and is_child_sum_met(root.right)
return False
return True
if __name__ == '__main__':
root = Node(10)
root.left = Node(8)
root.right = Node(2)
root.left.left = Node(3)
root.left.right = Node(5)
root.right.left = Node(2)
print is_child_sum_met(root)
"""
amzn
#tricky
http://www.geeksforgeeks.org/convert-an-arbitrary-binary-tree-to-a-tree-that-holds-children-sum-property/
"""
def increment_children(root, diff):
if root.left:
sum_of_children = sum_left + sum_right
value = root.data
root.data = sum_of_children
return sum_of_children + value
def is_leaf(node):
return node.left is None and node.right is None
if __name__ == '__main__':
_r = Node(10)
_r.left = Node(-2)
_r.right = Node(6)
_r.left.left = Node(8)
_r.left.right = Node(-4)
_r.right.left = Node(7)
_r.right.right = Node(5)
r = get_sum_tree(_r)
print r, r.left, r.left.left
def is_sum_tree(root):
if root is None:
return True, 0
is_left_st, left_sum = is_sum_tree(root.left)
is_right_st, right_sum = is_sum_tree(root.right)
is_left_balanced, left_height = is_balanced_bt(root.left)
is_right_balanced, right_height = is_balanced_bt(root.right)
if is_left_balanced and is_right_balanced:
return abs(left_height -
right_height) <= 1, max(left_height, right_height) + 1
return False, max(left_height, right_height) + 1
if __name__ == '__main__':
# balanced
root = Node(1)
root.left = Node(1)
root.right = Node(1)
root.left.left = Node(1)
root.left.right = Node(1)
root.left.right.left = Node(1)
root.right.right = Node(1)
print is_balanced_bt(root)
# not balanced
root = Node(1)
root.left = Node(1)
root.right = Node(1)
root.left.left = Node(1)
root.left.right = Node(1)
root.left.right.left = Node(1)
root.left.right.left.left = Node(1)
if root == node:
print_child_nodes_at_dist_k(root, k)
return 1
left_dist = print_at_dist_k(root.left, node, k)
right_dist = print_at_dist_k(root.right, node, k)
if left_dist > 0:
print_child_nodes_at_dist_k(root.right, k - (left_dist + 1))
return left_dist + 1
if right_dist > 0:
print_child_nodes_at_dist_k(root.left, k - (right_dist + 1))
return right_dist + 1
return -1
if __name__ == '__main__':
r = Node(1)
r.left = Node(2)
r.right = Node(3)
r.left.left = Node(4)
r.left.right = Node(5)
r.right.left = Node(6)
r.right.right = Node(7)
r.left.right.right = Node(8)
r.left.right.right.left = Node(9)
print_at_dist_k(r, r.left, 3)
"""
http://www.geeksforgeeks.org/find-pair-root-leaf-path-sum-equals-roots-data/
"""
from G4G.Problems.bst.vertical_sum import Node
def find_pair(root, hm, r_data):
if root:
if hm.get(r_data - root.data):
print 'YES', root.data, r_data - root.data
return
hm[root.data] = True
find_pair(root.left, hm, r_data)
find_pair(root.right, hm, r_data)
hm[root.data] = False
if __name__ == '__main__':
r = Node(8)
r.left = Node(5)
r.right = Node(4)
r.left.left = Node(9)
r.left.right = Node(7)
r.right.right = Node(11)
r.left.right.right = Node(12)
r.left.right.left = Node(1)
find_pair(r, {}, r.data)
return 0
l_sum = max(0, max_sum_path(root.left))
r_sum = max(0, max_sum_path(root.right))
# update max seen so far, l_sum = 0 means l_sum not considered
MAX_VAL = max(MAX_VAL, l_sum + r_sum + root.data)
# for parent use only one path. i.e. biggest path
return max(l_sum, r_sum) + root.data
if __name__ == '__main__':
r = Node(10)
r.left = Node(2)
r.right = Node(10)
r.left.left = Node(20)
r.left.right = Node(1)
r.right.right = Node(-25)
r.right.right.left = Node(3)
r.right.right.right = Node(4)
max_sum_path(r)
print MAX_VAL
"""
attempting some stuff
"""
return False
else:
done1 = False
done2 = False
if val1 is None and val2 is None:
return True
if val1 is None or val2 is None:
return False
if __name__ == '__main__':
r1 = Node(1)
r1.left = Node(2)
r1.right = Node(3)
r1.left.left = Node(4)
r1.right.left = Node(6)
r1.right.right = Node(7)
r2 = Node(0)
r2.left = Node(5)
r2.right = Node(8)
r2.left.right = Node(4)
r2.right.left = Node(6)
r2.right.right = Node(7)
print is_leaf_order_same(r1, r2)
r1 = Node(0)
r1.left = Node(1)
curr2 = s2.pop()
val2 = curr2.data
curr2 = curr2.left
done2 = True
# val1 != val2 makes sure that two of same values are not added
if val1 != val2 and val1 + val2 == target:
print 'pair found: {0} and {1}'.format(val1, val2)
return True
elif val1 + val2 < target:
done1 = False
elif val1 + val2 > target:
done2 = False
if val2 <= val1:
return False
if __name__ == '__main__':
r = Node(15)
r.left = Node(10)
r.right = Node(20)
r.left.left = Node(8)
r.left.right = Node(12)
r.right.left = Node(16)
r.right.right = Node(25)
print is_sum_pair_present(r, 33)
The maximum of them is 17 and the path for maximum is 7->10.
10
/ \
-2 7
/ \
8 -4
http://www.geeksforgeeks.org/find-the-maximum-sum-path-in-a-binary-tree/
"""
from G4G.Problems.bst.vertical_sum import Node
def max_sum_path(root, curr_sum):
if root is None:
return curr_sum
l_sum = max_sum_path(root.left, curr_sum + root.data)
r_sum = max_sum_path(root.right, curr_sum + root.data)
return max(l_sum, r_sum)
if __name__ == '__main__':
r = Node(10)
r.left = Node(-2)
r.right = Node(7)
r.left.left = Node(12)
r.left.right = Node(-4)
print max_sum_path(r, 0)
return True, right_node_dist + 1, right_min_dist
return False, 0, 0
def get_dist_of_closest_leaf(root, node):
is_found, ld, min_dist = find_closest(root, node)
if is_found:
return min_dist
return None
if __name__ == '__main__':
r = Node('A')
r.left = Node('B')
r.right = Node('C')
r.right.left = Node('E')
r.right.right = Node('F')
r.right.left.left = Node('G')
r.right.right.right = Node('H')
r.right.left.left.left = Node('I')
r.right.left.left.right = Node('J')
r.right.right.right.left = Node('K')
print get_dist_of_closest_leaf(r, 'H')
print get_dist_of_closest_leaf(r, 'C')
print get_dist_of_closest_leaf(r, 'E')
print get_dist_of_closest_leaf(r, 'B')
return node
def double_tree(root):
if root is None:
return None
root.left = double_tree(root.left)
root.right = double_tree(root.right)
return double_node(root)
if __name__ == '__main__':
root = Node(1)
root.left = Node(2)
root.right = Node(3)
double_tree(root)
print get_inorder_array(root, [])
root = Node(1)
root.left = Node(2)
root.right = Node(3)
root.left.left = Node(4)
root.left.right = Node(5)
double_tree(root)
print get_inorder_array(root, [])
print root,
def print_leaves(root):
if root:
print_leaves(root.left)
if is_leaf(root):
print root,
print_leaves(root.right)
def boundary_traversal(root):
top_down_left_traversal(root)
print_leaves(root)
bottom_up_right_traversal(root)
if __name__ == '__main__':
root = Node(20)
root.left = Node(8)
root.right = Node(22)
root.left.left = Node(4)
root.left.right = Node(12)
root.right.right = Node(25)
root.left.right.left = Node(10)
root.left.right.right = Node(14)
boundary_traversal(root)
