Problem
A pangram contains every English letter at least once. Determine whether the text is a pangram. Ignore case, spaces, digits, and punctuation.
Implement pangram_check(text).
Input
text: The text to inspect.
Output
Return true if all 26 letters appear, otherwise false.
Constraints
0 ≤ text length ≤ 100,000. Input contains printable ASCII characters. Only letters A–Z and a–z count.
Examples
Input:
text = "The quick brown fox jumps over the lazy dog."
Expected output:
expected = TrueInput:
std::string text = "The quick brown fox jumps over the lazy dog.";
Expected output:
bool expected = true;Input:
string text = "The quick brown fox jumps over the lazy dog.";
Expected output:
bool expected = true;Explanation
Every letter from a through z appears at least once. Capital T counts as t.
Input:
text = "abcdefghijklmnopqrstuvwxy"
Expected output:
expected = FalseInput:
std::string text = "abcdefghijklmnopqrstuvwxy";
Expected output:
bool expected = false;Input:
string text = "abcdefghijklmnopqrstuvwxy";
Expected output:
bool expected = false;Explanation
This text contains a through y, but it has no z. One missing letter makes it false.
How to approach it
Try on your own first, then open one hint at a time.
Hint 1
Normalize the text so letter case does not matter.
Hint 2
Track which of the 26 letters have appeared at least once.
Hint 3
Ignore every non-letter character completely, including spaces and punctuation.
Expected complexity
O(n) time, O(1) extra space
References
This challenge is adapted for CodeUtility. Follow the statement and constraints above.