Convert all lowercase characters to uppercase whose ASCII value is co-prime with k - GeeksforGeeks

15 Feb, 2022
Given an integer ‘k’ and a string ‘str’ consisting of characters from English alphabets. The task is to convert all lower case character to uppercase whose ASCII value is co-prime with k.Examples: 
Input: str = “geeksforgeeks”, k = 4 Output: GEEKSfOrGEEKS ‘f’ and ‘r’ are the only characters whose ASCII values aren’t co-prime with 4.Input: str = “Ac”, k = 2 Output: AC The only lower case character is ‘c’ and ASCII value of ‘c’ is 99 which is co-prime with 2.  
 
Approach:  
Iterate over all characters in the given string to check whether the current character is lowercase and if it’s ASCII value is co-prime with ‘k’
To check for co-prime, check that if the gcd of the value with k is ‘1’ or not.
If the above condition is satisfied then convert that lowercase alphabet to uppercase alphabet.
Below is the implementation of the above approach:  
C++
Java
Python3
C#
PHP
Javascript
// C++ implementation of the approach#include <bits/stdc++.h>using namespace std; // function to modify the stringvoid convert_str(string s, int k){    // length of the string    int l = s.length();     for (int i = 0; i < l; i++) {        int ascii = (int)s[i];         // check if the character is        // lowercase and co-prime with k        if (ascii >= 'a' && ascii <= 'z'            && __gcd(ascii, k) == 1) {             // change the character            // to upper-case            char c = s[i] - 32;            s[i] = c;        }    }     cout << s << "\n";} // Driver codeint main(){    string s = "geeksforgeeks";    int k = 4;     convert_str(s, k);     return 0;}
// Java implementation of the approachclass GFG{ // function to modify the string    static void convert_str(String str, int k)    {        // length of the string        char[] s = str.toCharArray();        int l = s.length;         for (int i = 0; i < l; i++)        {            int ascii = (int) s[i];             // check if the character is            // lowercase and co-prime with k            if (ascii >= 'a' && ascii <= 'z'                    && __gcd(ascii, k) == 1)            {                 // change the character                // to upper-case                char c = (char) (s[i] - 32);                s[i] = c;            }        }        System.out.println(String.valueOf(s));    }     static int __gcd(int a, int b)    {        // Everything divides 0        if (a == 0)         {            return b;        }        if (b == 0)        {            return a;        }         // base case        if (a == b)        {            return a;        }         // a is greater        if (a > b)        {            return __gcd(a - b, b);        }        return __gcd(a, b - a);    }     // Driver code    public static void main(String[] args)    {        String s = "geeksforgeeks";        int k = 4;        convert_str(s, k);    }} // This code is contributed by 29AjayKumar
# Python3 implementation of the approachfrom math import gcd # function to modify the stringdef convert_str(s, k):         modified_string = ""    for i in range(0, len(s)):        ascii = ord(s[i])         # check if the character is        # lowercase and co-prime with k        if (ascii >= ord('a') and            ascii <= ord('z') and            gcd(ascii, k) == 1):             # change the character to upper-case            modified_string += chr(ascii - 32)                     else:            modified_string += s[i]     print(modified_string) # Driver codeif __name__ == "__main__":     s = "geeksforgeeks"    k = 4     convert_str(s, k) # This code is contributed by Rituraj Jain
// C# implementation of the approachusing System; class GFG{     // function to modify the string    static void convert_str(String str, int k)    {             // length of the string        char[] s = str.ToCharArray();        int l = s.Length;         for (int i = 0; i < l; i++)        {            int ascii = (int) s[i];             // check if the character is            // lowercase and co-prime with k            if (ascii >= 'a' && ascii <= 'z'                    && __gcd(ascii, k) == 1)            {                 // change the character                // to upper-case                char c = (char) (s[i] - 32);                s[i] = c;            }        }        Console.WriteLine(String.Join("", s));    }     static int __gcd(int a, int b)    {        // Everything divides 0        if (a == 0)        {            return b;        }        if (b == 0)        {            return a;        }         // base case        if (a == b)        {            return a;        }         // a is greater        if (a > b)        {            return __gcd(a - b, b);        }        return __gcd(a, b - a);    }     // Driver code    public static void Main()    {        String s = "geeksforgeeks";        int k = 4;        convert_str(s, k);    }} // This code is contributed by PrinciRaj1992
<?php// PHP implementation of the approach // function to modify the stringfunction convert_str($str, $k){    // length of the string    $l = strlen($str);    $modified_string = "";     for ($i = 0; $i < $l; $i++)    {        $ascii = ord($str[$i]);         // check if the character is        // lowercase and co-prime with k        if ($ascii >= ord('a') &&            $ascii <= ord('z') &&            __gcd($ascii, $k) == 1)        {             // change the character to upper-case            $modified_string = $modified_string.chr($ascii - 32);        }        else        {            $modified_string = $modified_string.$str[$i];        }    }    echo ($modified_string);} function __gcd($a, $b){    // Everything divides 0    if ($a == 0)    {        return $b;    }    if ($b == 0)    {        return $a;    }     // base case    if ($a == $b)    {        return $a;    }     // a is greater    if ($a > $b)    {        return __gcd($a - $b, $b);    }    return __gcd($a, $b - $a);} // Driver code$s = "geeksforgeeks";$k = 4;convert_str($s, $k); // This code is contributed by ita_c?>
<script>      // JavaScript implementation of the approach      // function to modify the string      function convert_str(s, k) {        // length of the string        var l = s.length;        var newStr = "";         for (var i = 0; i < l; i++) {          var ascii = s[i].charCodeAt(0);           // check if the character is          // lowercase and co-prime with k          if (            ascii >= "a".charCodeAt(0) &&            ascii <= "z".charCodeAt(0) &&            __gcd(ascii, k) === 1          ) {            // change the character            // to upper-case            var c = String.fromCharCode(s[i].charCodeAt(0) - 32);            newStr += c;          } else {            newStr += s[i];          }        }        document.write(newStr);      }       function __gcd(a, b) {        // Everything divides 0        if (a === 0) {          return b;        }        if (b === 0) {          return a;        }         // base case        if (a === b) {          return a;        }         // a is greater        if (a > b) {          return __gcd(a - b, b);        }        return __gcd(a, b - a);      }       // Driver code       var s = "geeksforgeeks";      var k = 4;      convert_str(s, k);    </script>
GEEKSfOrGEEKS
 
Time Complexity: O(L), where L is the length of string.
Auxiliary Space: O(1)
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