Missing characters to make a string Pangram

Pangram is a sentence containing every letter in the English alphabet. Given a string, find all characters that are missing from the string, i.e., the characters that can make string a Pangram. We need to print output in alphabetic order.

Examples:

Input : welcome to geeksforgeeks
Output : abdhijnpquvxyz

Input : The quick brown fox jumps
Output : adglvyz

We have discussed Pangram Checking. The idea is similar, we traverse given string and mark all visited characters. At the end, we print all those characters which are not visited.

Lowercase and Uppercase character are considered same.

// C++ program to find characters that needs
// to be added to make Pangram
#include<bits/stdc++.h>
using namespace std;
const int MAX_CHAR = 26;

// Returns characters that needs to be added
// to make str
string missingChars(string str)
{
    // A boolean array to store characters
    // present in string.
    bool present[MAX_CHAR] = {false};

    // Traverse string and mark characters
    // present in string.
    for (int i=0; i<str.length(); i++)
    {
        if (str[i] >= 'a' && str[i] <= 'z')
            present[str[i]-'a'] = true;
        else if (str[i] >= 'A' && str[i] <= 'Z')
            present[str[i]-'A'] = true;
    }

    // Store missing characters in alphabetic
    // order.
    string res = "";
    for (int i=0; i<MAX_CHAR; i++)
        if (present[i] == false)
            res.push_back((char)(i+'a'));

    return res;
}

// Driver program
int main()
{
    string str = "The quick brown fox jumps "
                 "over the dog";
    cout << missingChars(str);
    return 0;
}        

Output:

alyz

Time Complexity : O(n)
Auxiliary Space : O(1)

This article is contributed by Pramod Kumar. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

GATE CS Corner    Company Wise Coding Practice

Recommended Posts:







Writing code in comment? Please use ide.geeksforgeeks.org, generate link and share the link here.