Check if the Sentence Is Pangram

Check if the Sentence Is Pangram - Problem

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.

Input & Output

Example 1 — Complete Pangram

$ Input: sentence = "thequickbrownfoxjumpsoverthelazydog"

› Output: true

💡 Note: This famous sentence contains every letter from a-z at least once, making it a pangram.

Example 2 — Missing Letters

$ Input: sentence = "leetcode"

› Output: false

💡 Note: Missing many letters like 'a', 'b', 'f', 'g', etc. Only contains: l, e, t, c, o, d (6 unique letters).

Example 3 — Short Sentence

$ Input: sentence = "abc"

› Output: false

💡 Note: Only contains 3 letters (a, b, c) out of the required 26 letters.

Constraints

1 ≤ sentence.length ≤ 1000
sentence consists of lowercase English letters only

Visualization

Tap to expand

Asked in

G Google 15 a Amazon 12 M Microsoft 8

The key insight is to track unique letters efficiently. Best approach uses a hash set with early termination - add each character to the set and return true immediately when size reaches 26. Time: O(n), Space: O(1).

Common Approaches

✓ Brute Force - Check Each Letter

⏱️ Time: O(26n) Space: O(1)

Iterate through all 26 letters of the alphabet. For each letter, scan the entire sentence to check if that letter appears at least once. Return true only if all 26 letters are found.

Frequency Count with Array

⏱️ Time: O(n) Space: O(1)

Create an array of size 26 to count frequency of each letter. Iterate through the sentence once to populate counts, then check if all 26 positions have at least 1 occurrence.

Hash Set - Optimal Solution

⏱️ Time: O(n) Space: O(1)

Add each character to a hash set as we iterate through the sentence. Since sets only store unique values, we can check if we've seen all 26 letters by checking if the set size equals 26. We can even return early once we reach 26.

Brute Force - Check Each Letter — Algorithm Steps

Step 1: Loop through each letter from 'a' to 'z'
Step 2: For each letter, scan the entire sentence
Step 3: If any letter is missing, return false
Step 4: If all letters found, return true

Visualization

Tap to expand

Step-by-Step Walkthrough

Check 'a'

Scan entire sentence for letter 'a'

Check 'b'

Scan entire sentence for letter 'b'

Continue

Repeat for all 26 letters

Code -

solution.c — C

#include <stdio.h>
#include <string.h>
#include <stdbool.h>

bool solution(char* sentence) {
    int len = strlen(sentence);
    // Check each letter a-z
    for (int i = 0; i < 26; i++) {
        char letter = 'a' + i;
        bool found = false;
        for (int j = 0; j < len; j++) {
            if (sentence[j] == letter) {
                found = true;
                break;
            }
        }
        if (!found) {
            return false;
        }
    }
    return true;
}

int main() {
    char sentence[1000];
    fgets(sentence, sizeof(sentence), stdin);
    sentence[strcspn(sentence, "\n")] = 0; // Remove newline
    bool result = solution(sentence);
    printf(result ? "true\n" : "false\n");
    return 0;
}

Time & Space Complexity

Time Complexity

⏱️

O(26n)

For each of 26 letters, we scan the sentence of length n

✓ Linear Growth

Space Complexity

O(1)

Only using a few variables, no extra data structures

✓ Linear Space

54.5K Views

Medium Frequency

~8 min Avg. Time

2.2K Likes

Ln 1, Col 1

Smart Actions

💡 Explanation

AI Ready

💡 Suggestion Tab to accept Esc to dismiss

// Output will appear here after running code

Code Editor Closed

Click the red button to reopen

Input & Output

Constraints

Visualization

Related Problems

Common Approaches

Brute Force - Check Each Letter — Algorithm Steps

Visualization

Code -

Time & Space Complexity

Select Compiler