A pangram is a sentence that contains every letter of the English alphabet at least once. The "Check if the Sentence Is Pangram" coding problem asks you to determine if a given string sentence (consisting of lowercase English letters) meets this criteria.
This is a standard "Easy" question used by companies like Microsoft, Goldman Sachs, and Google to assess basic string processing and hash set usage. It's a test of efficiency—can you identify that once you've seen all 26 letters, you can stop early? It evaluations your familiarity with character encoding (ASCII) and set-based data structures.
The pattern is Hash Table / Set counting. You iterate through the string and add each character to a Set. After the loop (or during the loop), you check if the size of the set is exactly 26. Alternatively, you can use a boolean array of size 26 or a bitmask (an integer where each bit represents a letter) to save space.
A common mistake is not handling non-alphabetic characters (though the problem usually specifies lowercase English letters). Another is using a full hash table when a simple boolean array or bitmask would be more memory-efficient. Some candidates might also forget that the alphabet has exactly 26 letters.
For problems involving a small, fixed set of keys (like the 26 letters of the alphabet), a bitmask is a highly efficient and "impressive" way to track seen elements. Practice using mask |= (1 << (char - 'a')) to set bits.
