Replace consonants with next immediate consonants alphabetically in a String

Given a string which contains lowercase English alphabets. The task is to replace each consonant with the next immediate consonant that comes in English alphabets.
Let’s say we have to replace character , it will be replaced by . Another example, let’s say we have to replace character , the next immediate consonant is , hence will be replaced by .

Note: If the character is ‘z’, then look circularly in English alphabets for the next consonant, i.e. replace it with ‘b’.

Examples: 

Input : str = "geeksforgeeks"
Output : heeltgosheelt

Input : str = "gfg"
Output : hgh

Approach:

• Iterate the string elements from left to right.
• If the string element is consonant, then check the next immediate alphabet of this element.
• If the next immediate alphabet is a consonant, then replace it with the this alphabet. If it is a vowel, then replace the string element with 2nd immediate alphabet as there are no consecutive vowels in English alphabets.

Below is the implementation of the above program: 

C++

// C++ program of above approach
#include <bits/stdc++.h>
using namespace std;

// Function to check if a character is
// vowel or not
bool isVowel(char ch)
{
    if (ch != 'a' && ch != 'e' && ch != 'i' && ch != 'o'
        && ch != 'u')
        return false;

    return true;
}

// Function that replaces consonant with
// next immediate consonant alphabetically
string replaceConsonants(string s)
{
    // Start traversing the string
    for (int i = 0; i < s.length(); i++) {

        if (!isVowel(s[i])) {

            // if character is z,
            // than replace it with character b
            if (s[i] == 'z')
                s[i] = 'b';
          // if character is Z,
            // than replace it with character B
            else if (s[i] == 'Z')
                {
                    s[i] = 'B';
                }
            // if the alphabet is not z
            else {

                // replace the element with
                // next immediate alphabet
                s[i] = (char)(s[i] + 1);

                // if next immediate alphabet is vowel,
                // than take next 2nd immediate alphabet
                // (since no two vowels occurs consecutively
                // in alphabets) hence no further
                // checking is required
                if (isVowel(s[i]))
                    s[i] = (char)(s[i] + 1);
            }
        }
    }

    return s;
}

// Driver code
int main()
{
    string s = "geeksforgeeks";

    cout << replaceConsonants(s);

    return 0;
}

Java

// Java program of above approach
class GFG {

    // Function to check if a character is
    // vowel or not
    static boolean isVowel(char ch)
    {
        if (ch != 'a' && ch != 'e' && ch != 'i' && ch != 'o'
            && ch != 'u') {
            return false;
        }
        return true;
    }

    // Function that replaces consonant with
    // next immediate consonant alphabetically
    static String replaceConsonants(char[] s)
    {
        // Start traversing the string
        for (int i = 0; i < s.length; i++) {
            if (!isVowel(s[i])) {

                // if character is z,
                // than replace it with character b
                if (s[i] == 'z') {
                    s[i] = 'b';
                }

                // if the alphabet is not z
                else {

                    // replace the element with
                    // next immediate alphabet
                    s[i] = (char)(s[i] + 1);

                    // if next immediate alphabet is vowel,
                    // than take next 2nd immediate alphabet
                    // (since no two vowels occurs
                    // consecutively in alphabets) hence no
                    // further checking is required
                    if (isVowel(s[i])) {
                        s[i] = (char)(s[i] + 1);
                    }
                }
            }
        }
        return String.valueOf(s);
    }

    // Driver code
    public static void main(String[] args)
    {
        String s = "geeksforgeeks";
        System.out.println(
            replaceConsonants(s.toCharArray()));
    }
}

// This code is contributed by Rajput-Ji

Python3

# Python3 program of above approach

# Function to check if a character is
# vowel or not


def isVowel(ch):

    if (ch != 'a' and ch != 'e' and
        ch != 'i' and ch != 'o' and
            ch != 'u'):
        return False

    return True

# Function that replaces consonant with
# next immediate consonant alphabetically


def replaceConsonants(s):

    # Start traversing the string
    for i in range(len(s)):
        if (isVowel(s[i]) == False):

            # if character is z,
            # than replace it with character b
            if (s[i] == 'z'):
                s[i] = 'b'

            # if the alphabet is not z
            else:

                # replace the element with
                # next immediate alphabet
                s[i] = chr(ord(s[i]) + 1)

                # if next immediate alphabet is vowel,
                # than take next 2nd immediate alphabet
                # (since no two vowels occurs consecutively
                # in alphabets) hence no further
                # checking is required
                if (isVowel(s[i]) == True):
                    s[i] = chr(ord(s[i]) + 1)

    return ''.join(s)


# Driver code
s = "geeksforgeeks"

print(replaceConsonants(list(s)))

# This code is contributed by mits

C#

// C# program of above approach
using System;

class GFG {

    // Function to check if a character is
    // vowel or not
    static bool isVowel(char ch)
    {
        if (ch != 'a' && ch != 'e' && ch != 'i' && ch != 'o'
            && ch != 'u') {
            return false;
        }
        return true;
    }

    // Function that replaces consonant with
    // next immediate consonant alphabetically
    static String replaceConsonants(char[] s)
    {

        // Start traversing the string
        for (int i = 0; i < s.Length; i++) {
            if (!isVowel(s[i])) {

                // if character is z,
                // than replace it with character b
                if (s[i] == 'z') {
                    s[i] = 'b';
                }

                // if the alphabet is not z
                else {

                    // replace the element with
                    // next immediate alphabet
                    s[i] = (char)(s[i] + 1);

                    // if next immediate alphabet is vowel,
                    // than take next 2nd immediate alphabet
                    // (since no two vowels occurs
                    // consecutively in alphabets) hence no
                    // further checking is required
                    if (isVowel(s[i])) {
                        s[i] = (char)(s[i] + 1);
                    }
                }
            }
        }
        return String.Join("", s);
    }

    // Driver code
    public static void Main(String[] args)
    {
        String s = "geeksforgeeks";
        Console.WriteLine(
            replaceConsonants(s.ToCharArray()));
    }
}

// This code is contributed by
// 29AjayKumar

PHP

<?php
// PHP program of above approach

// Function to check if a character is
// vowel or not
function isVowel($ch)
{
    if ($ch != 'a' && $ch != 'e' &&
        $ch != 'i' && $ch != 'o' &&
        $ch != 'u')
        return false;

    return true;
}

// Function that replaces consonant with
// next immediate consonant alphabetically
function replaceConsonants($s)
{
    // Start traversing the string
    for ($i = 0; $i < strlen($s); $i++)
    {
        if (!isVowel($s[$i]))
        {

            // if character is z,
            // than replace it with character b
            if ($s[$i] == 'z')
                $s[$i] = 'b';

            // if the alphabet is not z
            else
            {

                // replace the element with
                // next immediate alphabet
                $s[$i] = chr(ord($s[$i]) + 1);

                // if next immediate alphabet is vowel,
                // than take next 2nd immediate alphabet
                // (since no two vowels occurs consecutively
                // in alphabets) hence no further
                // checking is required
                if (isVowel($s[$i]))
                    $s[$i] = chr(ord($s[$i]) + 1);
            }
        }
    }
    return $s;
}

// Driver code
$s = "geeksforgeeks";

echo replaceConsonants($s);

// This code is contributed by mits
?>

Javascript

<script>

// Javascript program of above approach

// Function to check if a character is
// vowel or not
function isVowel(ch)
{
    if (ch != 'a' && ch != 'e' && ch != 'i'
                     && ch != 'o' && ch != 'u')
        return false;

    return true;
}

// Function that replaces consonant with
// next immediate consonant alphabetically
function replaceConsonants(s)
{
    // Start traversing the string
    for (var i = 0; i < s.length; i++) {

        if (!isVowel(s[i])) {

            // if character is z,
            // than replace it with character b
            if (s[i] == 'z')
                s[i] = 'b';

            // if the alphabet is not z
            else {

                // replace the element with
                // next immediate alphabet
                s[i] = String.fromCharCode(s[i].charCodeAt(0) + 1);

                // if next immediate alphabet is vowel,
                // than take next 2nd immediate alphabet
                // (since no two vowels occurs consecutively
                // in alphabets) hence no further
                // checking is required
                if (isVowel(s[i]))
                    s[i] = String.fromCharCode(s[i].charCodeAt(0) + 1);
            }
        }
    }

    return s.join('');
}

// Driver code
var s = "geeksforgeeks".split('');
document.write( replaceConsonants(s));


</script>

Output

heeltgosheelt

Complexity Analysis:

• Time Complexity: O(n), where n is the size of string s 
• Auxiliary Space: O(1)