Problem

Given a string, write a Python function to check if the string is a pangram or not.
Pangrams are words or sentences containing every letter of the alphabet at least once.
For example: "The quick brown fox jumps over the lazy dog" is a pangram.
Input: "hello world"
Output: False

Solution

# Solution:

def is_pangram(s):
    alphabet = "abcdefghijklmnopqrstuvwxyz"
    for char in alphabet:
        if char not in s:
            return False
    return True

# Explanation:

# The solution above is optimal because it uses a for loop to iterate through the alphabet string.
# It then checks if each character in the alphabet string is in the input string.
# If it is not, it returns False.
# If it is, it continues to the next character in the alphabet string.
# If it makes it through the entire alphabet string, it returns True.
# This solution is optimal because it only iterates through the alphabet string once.
# It also only iterates through the input string once.
# This is optimal because it is O(n) time complexity.