Given a sorted dictionary of an alien language, find the order of characters. This is topological sort on character ordering.
Compare adjacent words to find character orderings (edges). Then topological sort. If cycle exists, return empty string.
💡 Pro tip: Understand this problem deeply — don't just memorize the code. Try explaining the approach out loud as if teaching a friend. If you can explain it simply, you truly understand it!
alienOrder(['wrt','wrf','er','ett','rftt'])
wertf