Solutions for Google Code Jam 2019 Round 1A at https://codingcompetitions.withgoogle.com/codejam/round/0000000000051635.

swift run Pylons < data/Pylons.in

$N = 365$ and $M = 100$ in this test set.

python interactive_runner.py python data/GolfGophers.py 0 -- swift run GolfGophers

$N = 7$ and $M = 10^6$ in this test set.

python interactive_runner.py python data/GolfGophers.py 1 -- swift run GolfGophers

I've created two solutions and wrote additional test cases.

This solution greedily finds the longest matching suffix and removes pairs from a linked list.

g++ -std=c++14 alien_rhyme.cpp && ./a.out < data/AlienRhyme.in

This solution uses a prefix tree (also called it a trie) and recursively finds pairs in different subtrees.

swift run AlienRhyme < data/AlienRhyme.in