@recticodedotcom

real world debugging practice, not algorithms prove you can debug real systems

recticode.com
Joined May 2026
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most coding platforms test algorithms. recticode tests whether you can debug real systems. multi-file projects. subtle bugs. real commit history. build a public debugging track record. recticode.com
what the cli looks like

ALT what the cli looks like

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it's live. the recticode challenge sprint is now open. build a realistic debugging challenge: • multi-file project • subtle production-style bug the best submissions become official recticode challenges used in the debugging championship this august. link in bio!
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daily debug #6 what does it print? reply with: - the output - why it happens answer tomorrow.
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most programming competitions reward writing code. recticode also rewards understanding it. because every engineer eventually inherits a codebase they didn't write. that's where debugging starts.
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daily debug #6 what does it print? reply with: - the output - why the two lines are different answer tomorrow.
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answer: ['a', 'b', 'c', 'a', 'b', 'c'] [['a', 'b', 'c'], ['a', 'b', 'c']] the first duplicates the contents of the list. the second duplicates references to the same list, not copies.
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daily debug #5 what does it print? reply with: - the output - why it happens answer tomorrow.
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answer: {'users': ['alice', 'bob', 'charlie']} {'users': ['alice', 'bob', 'charlie']} dict.copy() only performs a shallow copy. both dictionaries still reference the same list object, so modifying backup["users"] also modifies data. fix: copy.deepcopy(data)
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the best debugging challenges don't have impossible bugs. they have believable bugs. the kind where you spend 30 minutes convinced the problem is in one file... before realising it was somewhere completely different. that's what we're trying to recreate with recticode.
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daily debug #4 what does it print? reply with: - the output - why it happens answer tomorrow.
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answer: it prints [80, 90, 100]. score is just a loop variable, so changing it doesn’t update the list. use indices or a list comprehension.
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recticode now has 2 phases: challenge sprint: july 16-31 create debugging challenges debugging championship: august 1-7 solve challenges + climb leaderboard all accepted challenges become part of challenge library if you enjoy creating production-style bugs, now's your chance
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most bugs don’t look broken at first. they look reasonable. they pass basic tests. they hide inside code you think you understand. that’s why debugging is such a good test of engineering skill. that's why recticode is starting with python debugging challenges.
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daily debug #3 what does it print? reply with: - the output - why it happens answer tomorrow.
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answer: it prints both alice and bob, because "owner" is always truthy. a valid fix would either be: - replace with user["role"] == "admin" or user["role"] == "owner" - replace with user["role"] in ["admin", "owner"]
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debugging is basically detective work for code. you collect clues. you test assumptions. you follow traces. you rule things out. the final fix might be one line. but the real skill is finding which line.
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daily debug #2 what does it print? reply with: - the output - why it happens answer tomorrow.
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answer: all three print 4. the lambdas capture the variable i, not its value at creation time. by the time they're called, i == 2, so every lambda uses 2.
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every engineer remembers a bug that took hours to find. not because it was complicated. because the code looked correct. those are the bugs that teach you the most. recticode is built around that idea: less toy problems. more realistic debugging.
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daily debug #1 what does this print? (most people get this wrong) reply with: - the output - why it happens answer tomorrow.
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answer: output: ['alice'] ['alice', 'bob']
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