Rating:

# Missing Pieces
We’re presented with the file “flag.txt” containing 32 lists of numbers. Each list consists of 255 different numbers in range [0, 255] (256 possible values). We can notice that only one value from range [0, 255] is missing from each list, hence the name of the task is “Missing Pieces”. Combining missing values from each list we get the flag.
Solution in python:

```
# lists from file flag.txt
data = [[...]]

ans = []
for v in data:
for i in range(256):
if i not in v:
ans.append(i)

ans = ''.join(map(chr, ans))
print(ans)
```

Screenshot with script execution:

![](https://raw.githubusercontent.com/kukuxumushi/HTBxUNI-CTF-final-writeups/master/pictures/2021-03-26-22-39-54.png)

Original writeup (https://github.com/kukuxumushi/HTBxUNI-CTF-final-writeups/blob/master/Missing_Pieces.md).