ErrLookup › donnemartin/interactive-coding-challenges
donnemartin/interactive-coding-challenges
120+ interactive Python coding interview challenges (algorithms and data structures). Includes Anki flashcards. · Python · 261 source files
Analyzed at 358f2cc604 on 2026-08-28. 75 documented errors.
| Code / Message | Type | Severity | Tags |
|---|---|---|---|
| a or b cannot be None | exception | error | python, input-validation, typeerror, bit-manipulation, recursion |
| sentence cannot be None | exception | error | python, input-validation, typeerror, algorithm |
| Cannot have a None input | exception | error | python, input-validation, typeerror, recursion, hanoi |
| Stack full | exception | error | python, stack, capacity, overflow, data-structure |
| Invalid start or end node key | exception | error | python, graph, dijkstra, keyerror, validation |
| s or t cannot be None | exception | error | python, input-validation, typeerror, strings |
| neighbor or weight cannot be None | exception | error | python, graph, none-check, edge-weight |
| coins or total cannot be None | exception | error | python, input-validation, typeerror, dynamic-programming |
| Input node keys cannot be None | exception | error | python, graph, dijkstra, none-check |
| root cannot be None | exception | error | python, binary-tree, none-check, validation |
| matrix and val cannot be None | exception | error | python, input-validation, typeerror, matrix-search |
| rows and cols cannot be None | exception | error | python, input-validation, typeerror, algorithm |
| graph cannot be None | exception | error | python, graph, dijkstra, none-check, constructor |
| Invalid key | exception | error | python, graph, keyerror, edge-validation |
| num cannot be negative | exception | error | math, digits, validation, python |
| input_items or total_weight cannot be None | exception | error | python, dynamic-programming, knapsack, input-validation, typeerror |
| Stack is full | exception | error | python, stack, overflow, capacity, data-structure |
| array cannot be None or empty | exception | error | python, input-validation, typeerror, bit-manipulation |
| neighbor not found | exception | error | python, graph, keyerror, edge-removal |
| items or total_weight cannot be None | exception | error | python, knapsack, unbounded, dynamic-programming, input-validation |
| num cannot be None | exception | error | math, digits, none-guard, python |
| string must be of type str | validation | error | python, type-check, string, sliding-window, input-validation |
| rows and cols cannot be negative | validation | error | python, input-validation, valueerror, algorithm |
| prices must have at least two values | validation | error | python, input-validation, algorithm, valueerror |
| array or val cannot be None | exception | error | python, input-validation, typeerror, binary-search |
| word does not exist | validation | error | trie, remove, keyerror, word-not-found |
| end indices must be >= 0 | exception | error | python, merge, array, valueerror, index-validation |
| num_pairs cannot be < 0 | validation | error | python, valueerror, recursion, backtracking, input-validation |
| ransom_note or magazine cannot be None | exception | error | python, null-check, string, typeerror |
| neighbor cannot be None | exception | error | python, graph, none-check, edge-removal |
| Index cannot be negative | validation | error | python, value-error, negative-index, bit-manipulation |
| nums cannot be empty | validation | error | two-sum, empty-list, valueerror, validation |
| data cannot be None | exception | error | python, input-validation, typeerror, merge-sort |
| key cannot be None | exception | error | python, graph, none-check, node-key |
| num_pairs cannot be None | exception | error | python, recursion, backtracking, parentheses, input-validation |
| word cannot be None | exception | error | trie, string, none-guard, python |
| val cannot be None | exception | error | python, input-validation, none-check, statistics |
| array cannot be None | exception | error | python, null-check, input-validation, typeerror |
| num cannot be 0 or negative | validation | error | python, value-error, bit-manipulation, non-positive-input |
| Invalid event type | exception | error | python, enum, input-validation, intervals, event-processing |
| str input cannot be None | exception | error | python, dynamic-programming, string, lcs, input-validation |
| nums cannot be None | exception | error | python, null-check, in-place, typeerror |
| num_steps cannot be None or negative | exception | error | python, recursion, memoization, dynamic-programming, input-validation |
| Invalid index | validation | error | python, bit-manipulation, index-error, argument-validation |
| k must be of type int | validation | error | python, type-check, integer, sliding-window, input-validation |
| root must have at least one child | validation | error | python, bst, tree, insufficient-data, value-error |
| Invalid arg: Empty screen or width | validation | error | python, value-error, empty-buffer, graphics, argument-validation |
| max_num cannot be None | exception | error | python, input-validation, none-check, primes, sieve |
| license_key must be a str | exception | error | python, input-validation, none-check, strings, formatting |
| prices or k cannot be None | exception | error | python, dynamic-programming, stocks, input-validation |
| greed_indices or cookie_sizes cannot be None | exception | error | python, input-validation, none-check, greedy, arrays |
| Key not found | validation | error | hash-map, keyerror, key-not-found |
| license_key must not be empty | exception | error | python, input-validation, empty-string, strings |
| array must have 3 or more ints | validation | error | python, input-validation, algorithm, valueerror |
| seq cannot be None | exception | error | python, dynamic-programming, subsequence, input-validation |
| root is None | exception | error | tree, bfs, traversal, none-guard, python |
| source or dest cannot be None | exception | error | python, merge, array, input-validation, typeerror |
| Stack is empty | exception | error | python, stack, underflow, data-structure |
| str1 or str2 cannot be None | validation | error | string-diff, none-check, typeerror, validation |
| Invalid argument: None | validation | error | python, bit-manipulation, graphics, type-error, none-check |
| matrices cannot be None | exception | error | python, dynamic-programming, matrix-chain, input-validation |
| nums or target cannot be None | validation | error | two-sum, none-check, typeerror, validation |
| items cannot be None | exception | error | python, anagram, hashing, input-validation |
| num cannot be less than one | validation | error | fizz-buzz, range-validation, valueerror |
| prices cannot be None | exception | error | python, input-validation, none-check, arrays, greedy |
| Invalid value | validation | error | python, bit-manipulation, value-validation, generic-exception |
| file_system cannot be None | exception | error | python, input-validation, none-check, strings, file-paths |
| node cannot be None | exception | error | python, bst, successor, tree-traversal, none-check |
| string cannot be None | exception | error | python, input-validation, none-check, strings, sliding-window |
| k cannot be None | exception | error | python, input-validation, none-check, sliding-window |
| number cannot be None | validation | error | python, constructor, type-error, none-check |
| grid cannot be None | exception | error | python, input-validation, none-check, matrix, grid |
| Invalid arg: x1 or x2 out of bounds | validation | error | python, out-of-bounds, value-error, graphics, off-by-one |
| Argument cannot be None | validation | error | python, bit-manipulation, type-error, none-check |
| n cannot be None | exception | error | python, input-validation, none-check, bit-manipulation |