Date: 2026-06-06
Time: 15:43
check-if-the-sentence-is-pangram/solution.pySolves LeetCode 1832 — Check if the Sentence Is Pangram. A pangram is a sentence that contains every letter of the English alphabet at least once. This file owns the solution logic and exposes it via the Solution class, following LeetCode's expected interface.
Solution.min_operations(self, sentence: str) -> bool
The sole method. Note the name mismatch: LeetCode names this problem's method checkIfPangram, but this implementation uses min_operations — likely a copy-paste artifact from another solution's scaffold. The method name doesn't affect correctness since the test harness imports and calls whatever is defined on Solution.
Contract: Takes a string of lowercase English letters, returns True if all 26 letters are present.
Set-based membership check: set(sentence) deduplicates the input into unique characters, then the length is compared against 26 (the size of the lowercase English alphabet). This is a common Python idiom for "are all categories represented" problems — O(n) time, O(1) space (the set is bounded at 26 elements regardless of input length).
LeetCode Solution class convention: Every solution in this repo wraps its logic in a Solution class with a single method, matching LeetCode's submission format.
Imports: None — uses only Python builtins (set, len).
Imported by: The check-if-the-sentence-is-pangram/test_solution.py file (and the massive "Imported By" list in the prompt is the repo-wide test suite importing Solution from their own respective solution.py files, not from this one).
1. set(sentence) — scans the entire string, building a set of unique characters. For input "thequickbrownfoxjumpsoverthelazydog", this produces {'t','h','e','q',...} with 26 elements.
2. len(...) — counts the unique characters.
3. == 26 — if exactly 26, every letter a–z appeared at least once.
No loops, no branching, no mutation — a single expression.
set() would include them and the length check would fail even for a valid pangram like "The Quick Brown Fox...". The docstring documents this constraint.None. No input validation, no exceptions. The function trusts its caller to provide a valid lowercase-only string, which is appropriate for a LeetCode solution where input constraints are guaranteed by the judge.
check-if-the-sentence-is-pangram/test_solution.py — See how the test harness exercises edge cases (empty string, 25-letter input, exact pangram)check-if-the-sentence-is-pangram/review.md — Contains the code review notes for this solution, likely flags the method name mismatchcheck-if-all-characters-have-equal-number-of-occurrences/solution.py:Solution — Related set/Counter pattern for character frequency problemsset-vs-bitmask-pangram — An alternative approach uses a 26-bit integer bitmask (seen |= 1 << (ord(c) - ord('a'))) to avoid heap allocation entirelypangram-set-length-26 — set(sentence) having length 26 is both necessary and sufficient for a pangram when the input contains only lowercase English letterspangram-method-name-mismatch — The method is named min_operations rather than checkIfPangram, diverging from LeetCode's canonical signaturepangram-no-imports — The solution uses zero imports; set and len are Python builtinspangram-assumes-lowercase-only — The correctness of the length-26 check depends on the input containing no characters outside a–z