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#!/usr/bin/env python3
# Challenge 057
#
# TASK #1 › Invert Tree
# You are given a full binary tree of any height, similar to the one below:
#
#
#
# Write a script to invert the tree, by mirroring the children of every node,
# from left to right. The expected output from the tree above would be:
#
#
#
# The input can be any sensible machine-readable binary tree format of your
# choosing, and the output should be the same format.
#
# BONUS
# In addition to the above, you may wish to pretty-print your binary tree in a
# human readable text-based format similar to the following:
#
# 1
# / \
# 3 2
# / \ / \
# 7 6 5 4
import fileinput
import re
import sys
class Node:
def __init__(self, value):
self.value = value
self.left = None
self.right = None
def __repr__(self):
return "Node(value: {}, left: {}, right: {})" \
.format(self.value, self.left, self.right)
def read_input():
lines = []
for line in fileinput.input():
lines.append(line)
return lines
def parse_subtree(lines, row, col):
def ch(row, col):
if row < 0 or row >= len(lines) or \
col < 0 or col >= len(lines[row]):
return ' '
else:
return lines[row][col]
tree = Node(int(lines[row][col]))
if ch(row + 1, col - 1) == '/':
tree.left = parse_subtree(lines, row + 2, col - 2)
if ch(row + 1, col + 1) == '\\':
tree.right = parse_subtree(lines, row + 2, col + 2)
return tree
def parse_tree(lines):
found = re.search(r'^[ ]+\d', lines[0])
col = found.span()[1] - 1
return parse_subtree(lines, 0, col)
def invert_tree(tree):
if tree:
tree.left, tree.right = tree.right, tree.left
invert_tree(tree.left)
invert_tree(tree.right)
def dump_tree(tree):
if tree:
print(tree.value, end='')
if tree.left or tree.right:
print("(", end='')
dump_tree(tree.left)
print("|", end='')
dump_tree(tree.right)
print(")", end='')
tree = parse_tree(read_input())
invert_tree(tree)
dump_tree(tree)
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