Change string to a new character set

Given a 26 letter character set, which is equivalent to character set of English alphabet i.e. (abcd….xyz) and act as a relation. We are also given several sentences and we have to translate them with the help of given new character set.

Examples:

New character set : qwertyuiopasdfghjklzxcvbnm
Input : "utta"
Output : geek

Input : "egrt"
Output : code

Idea behind conversion of new character set is to use hashing. Perform hashing of new character set where element of set is index and its position will be new alphabet value. 

Approach1:

Given New character set = "qwertyuiopasdfghjklzxcvbnm" 
First character is q, during hashing we will place 'a' (for position )
at index q i.e. (17th).
After hashing our new character set is "kxvmcnophqrszyijadlegwbuft".
For input "egrt" = 
      hash[e -'a'] = c 
      hash[g -'a'] = o 
      hash[r -'a'] = d 
      hash[t -'a'] = e
For "egrt" is equivalent to "code".

Implementation:

C++

// CPP program to change the sentence
// with virtual dictionary
#include<bits/stdc++.h>
using namespace std;

// Converts str to given character set
void conversion(char charSet[], string &str)
{
    int n = str.length();

    // hashing for new character set
    char hashChar[26];
    for (int i = 0; i < 27; i++)
        hashChar[charSet[i]-'a'] = 'a' + i;

    // conversion of new character set
    for (int i = 0; i < n; i++)
        str[i] = hashChar[str[i]-'a'];
}

// Driver code
int main()
{
    char charSet[27] = "qwertyuiopasdfghjklzxcvbnm";
    string str = "egrt";
    conversion(charSet, str);
    cout << str;
    return 0;
}

Java

// Java program to change the sentence
// with virtual dictionary
class GFG {

// Converts str to given character set
    static String conversion(char charSet[], String str) {
        int n = str.length();

        // hashing for new character set
        char hashChar[] = new char[26];
        for (int i = 0; i < 26; i++) {
            int ch = Math.abs(charSet[i] - 'a');
            hashChar[ch] = (char) ('a' + i);
        }

        // conversion of new character set
        String s="";
        for (int i = 0; i < n; i++) {
            s += hashChar[str.charAt(i) - 'a'];
        }
        return s;
    }

// Driver code
    public static void main(String[] args) {
        char charSet[] = "qwertyuiopasdfghjklzxcvbnm".toCharArray();
        String str = "egrt";
        str = conversion(charSet, str);
        System.out.println(str);
// This code is contributed by princiRaj1992
    }
}

Python3

# Python3 program to change the sentence
# with virtual dictionary
from string import ascii_lowercase

# Function to convert the string using the given charset
def conversion(char_set: str, string: str) -> str:
    #hashing for new character set
    hash_char = dict()

    for alphabet, new_char in zip(ascii_lowercase, char_set):
        hash_char[new_char] = alphabet

    # conversion of new character set
    string2 = ""
    for i in string:
        string2 += hash_char[i]

    return string2

# Driver Code
if __name__ == "__main__":
    char_set = "qwertyuiopasdfghjklzxcvbnm"
    string = "egrt"

    print(conversion(char_set, string))

    # This code is contributed by kraanzu.

C#

// C# program to change the sentence
// with virtual dictionary
using System;

class GFG
{

    // Converts str to given character set
    static String conversion(char []charSet,
                             String str)
    {
        int n = str.Length;

        // hashing for new character set
        char []hashChar = new char[26];
        for (int i = 0; i < 26; i++)
        {
            int ch = Math.Abs(charSet[i] - 'a');
            hashChar[ch] = (char) ('a' + i);
        }

        // conversion of new character set
        String s = "";
        for (int i = 0; i < n; i++)
        {
            s += hashChar[str[i] - 'a'];
        }
        return s;
    }

    // Driver code
    public static void Main(String[] args)
    {
        char []charSet = "qwertyuiopasdfghjklzxcvbnm".ToCharArray();
        String str = "egrt";
        str = conversion(charSet, str);
        Console.WriteLine(str);
    }
}

// This code is contributed by Princi Singh

Javascript

<script>
// Javascript program to change the sentence
// with virtual dictionary

// Converts str to given character set
function conversion(charSet, str)
{
    var n = str.length;

    // hashing for new character set
    var hashChar = Array(26);
    for (var i = 0; i < 26; i++)
     {
       var ch = Math.abs(charSet[i].charCodeAt(0)-
        'a'.charCodeAt(0));
        hashChar[ch] =
        String.fromCharCode('a'.charCodeAt(0) + i);
}
    var s = "";

    // conversion of new character set
    for (var i = 0; i < n; i++)
        s += (hashChar[str[i].charCodeAt(0)-'a'.charCodeAt(0)]);
    return s;
}

// Driver code
var charSet = "qwertyuiopasdfghjklzxcvbnm".split('');
var str = "egrt";
str = conversion(charSet, str);
document.write( str);

// This code is contributed by importantly.
</script>

Output

code

Time Complexity: O(N) where N is length of string.
Auxiliary Space: O(1) 

Approach2:

1. Initialize two strings, one with actual set of alphabets and another with modified one. 
2. Get the string to be converted from the user. 
3. Retrieve the first element of the string, find its index in the modified set of alphabets(eg:0 for ‘q’). 
4. Find the element of same index in the actual set of alphabets and concatenate it with the result string. 
5. Repeat the above steps for all the remaining elements of the input string. 
6. Return the result string. 

C++

// CPP program to change the sentence
// with virtual dictionary
#include <bits/stdc++.h>
using namespace std;

// Converts str to given character set
string conversion(string charSet, string str)
{
    string alphabets = "abcdefghijklmnopqrstuvwxyz";
    string s2 = "";

    for (char i : str) {
        s2 += alphabets[charSet.find_first_of(i)];
    }

    return s2;
}

// Driver code
int main()
{
    string charSet = "qwertyuiopasdfghjklzxcvbnm";
    string str = "egrt";
    cout << conversion(charSet, str);
    return 0;
}

Java

// Java program to change the sentence
// with virtual dictionary

class GFG
{
    static char[] alphabets = "abcdefghijklmnopqrstuvwxyz".toCharArray();

    // function for converting the string
    static String conversion(String charSet, char[] str1)
    {
        String s2 = "";
        for (char i : str1)

            // find the index of each element of the
            // string in the modified set of alphabets
            // replace the element with the one having the
            // same index in the actual set of alphabets
            s2 += alphabets[charSet.indexOf(i)];

        return s2;
    }

    // Driver Code
    public static void main(String[] args)
    {
        String charSet = "qwertyuiopasdfghjklzxcvbnm";
        String str1 = "egrt";
        System.out.print(conversion(charSet, str1.toCharArray()));
    }
}

// This code is contributed by PrinciRaj1992

Python3

# Python3 program to change the sentence
#  with virtual dictionary

#function for converting the string
def conversion(charSet,str1):
    s2=""
    for i in str1:
        # find the index of each element of the
        # string in the modified set of alphabets
        # replace the element with the one having the
        # same index in the actual set of alphabets
        s2 += alphabets[charSet.index(i)]

    return s2

# Driver Code
if __name__=='__main__':
    alphabets = "abcdefghijklmnopqrstuvwxyz"
    charSet= "qwertyuiopasdfghjklzxcvbnm"
    str1 = "egrt"
    print(conversion(charSet,str1))

#This code is contributed by PradeepEswar

C#

// C# program to change the sentence
// with virtual dictionary
using System;

class GFG
{
    static char[] alphabets = "abcdefghijklmnopqrstuvwxyz".ToCharArray();

    // function for converting the string
    static String conversion(String charSet, char[] str1)
    {
        String s2 = "";
        foreach (char i in str1)

            // find the index of each element of the
            // string in the modified set of alphabets
            // replace the element with the one having the
            // same index in the actual set of alphabets
            s2 += alphabets[charSet.IndexOf(i)];

        return s2;
    }

    // Driver Code
    public static void Main(String[] args)
    {
        String charSet = "qwertyuiopasdfghjklzxcvbnm";
        String str1 = "egrt";
        Console.Write(conversion(charSet, str1.ToCharArray()));
    }
}

// This code is contributed by Rajput-Ji

Javascript

<script>
      // JavaScript program to change the sentence
      // with virtual dictionary
      var alphabets = "abcdefghijklmnopqrstuvwxyz".split("");

      // function for converting the string
      function conversion(charSet, str1) {
        var s2 = "";
        str1.forEach((i) => {
          // find the index of each element of the
          // string in the modified set of alphabets
          // replace the element with the one having the
          // same index in the actual set of alphabets
          s2 = s2 + alphabets[charSet.indexOf(i)];
        });
        return s2;
      }

      // Driver Code
      var charSet = "qwertyuiopasdfghjklzxcvbnm";
      var str1 = "egrt";
      document.write(conversion(charSet, str1.split("")));

      // This code is contributed by rdtank.
    </script>

Output

code

Time Complexity: O(N) where N is length of string.
Auxiliary Space: O(1).