Not OP, but I was pretty disappointed trying Claude 4.6

Prompted

Write a C program to find the longest word in a static 5x5 array of characters.

These characters shall be defined in a header file, you may allocate it with any letters for now

This program should find the longest word, using words available in a file at /usr/share/dict/words
This file will have one word per line

The rules of the longest word are that you may select the next letter in any direction from your current letter one character away, including diagonals

Any index may be the starting point, and you may not repeat a space on the grid

It did a breadth first search for the longest path, then checked if that longest path was a word, rather than checking each step, so it never found any words

When I asked it to fix that, it then opened and reread the entire dictionary for each character

Once I got it to fix that, I asked it to read the input array from a file, and after 30 minutes of asking it in different ways, it never managed to successfully read that file in

All in all, it took longer than just writing it myself, even for what I would call an interview question