CTFlearn-Writeups/Programming/Simple Programming

Simple Programming

The main idea finding the flag is some simple counting in a file.

Step-1:

After we download data.dat from the cloud, we understand that it is has 10,000 lines. So we definitely need to write up a script to get answer.

Step-2:

So I quickly drafted up Flag.py script to get number of such lines:

count = 0

file = 'data.dat'

with open(file) as f:    
        l = f.readlines()
        for line in l:
                zero = line.count('0')
                one = line.count('1')
                '''the condition where the number of '0' is divisible by 3 
                OR the number of '1' is divisible by 2'''
                if (zero%3 == 0) or (one%2 == 0):
                        count = count + 1

print("Number of lines: " + str(count))
f.close()

Step-3:

When we execute this script by python3 Flag.py, we get the flag.

Output: Number of lines: 6662

Step-4:

Finally the flag becomes: CTFlearn{6662}