1832_Check_if_the_Sentence_Is_Pangram.cpp

/*
1832. Check if the Sentence Is Pangram
A pangram is a sentence where every letter of the English alphabet appears at 
least once.
Given a string sentence containing only lowercase English letters, return 
true if sentence is a pangram, or false otherwise.
Example 1:
Input: sentence = "thequickbrownfoxjumpsoverthelazydog"
Output: true
Explanation: sentence contains at least one of every letter of the English alphabet.
Example 2:
Input: sentence = "leetcode"
Output: false
Constraints:
1 <= sentence.length <= 1000
sentence consists of lowercase English letters.
*/
class Solution {
public:
// Time Complexity o(n)
// Space Complexity O(1)
    bool checkIfPangram(string sentence) {
        unordered_map<char,int> freq;
        for(char &ch:sentence){
            if(isalpha(ch)){
                freq[ch]++;
            }
        }
        return freq.size()==26?1:0;
    }
};