1832 Check if the Sentence Is Pangram

Intuition

We use set to check if the sentence given has all the alphabet.

We are using set arithmetic, namely difference → set(A) - set(B) will create a set of all elements in A but not in B. So naturally, set A must be greater than B.

If you are interested in learning more about set arithmetic, look into set union, set intersection and set difference. Check out this link

Code

Python3

def checkIfPangram(self, sentence: str) -> bool:
    return len(set(string.ascii_lowercase) - set(sentence)) == 0

Big O Analysis

• Runtime

  The runtime complexity here is $O(N)$ since we are converting the sentence of length N into a set. If N < 26, then it’s O(26) cuz of the string.ascii_lowercase).

• Memory

  The memory usage is $O(N)$ since we are in-fact using sets.

— A

GitHub | Twitter