You are given 128 puzzles (https://en.wikipedia.org/wiki/15_puzzle) The ith puzzle determines the ith bit of the flag:

• 1 if the puzzle is soluble
• 0 if the puzzle is unsoluble Implement is_soluble() below, and use the code to get the flag!

Note: There is an important note on the News page about this challenge.

def is_soluble(i): return 0 flag = ' ' for i in range(128): flag = ('1' if is_soluble(i) else '0') + flag print('SharifCTF{%016x}' % int(flag, 2)) Download