Substring Reverse Pattern

Given a string str, the task is to print the pattern given in the examples below:

Examples:

Input: str = “geeks”
Output:
geeks
*kee*
**e**
Reverse of “geeks” is “skeeg”
Replace first and last character with ‘*’ i.e. *kee*
Replace second and second last character in the modified string i.e. **e**
And so on.

Input: str = “first”
Output:
first
*sri*
**r**

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach:

• Print the unmodified string.
• Reverse the string and initialize i = 0 and j = n – 1.
• Replace s[i] = ‘*’ and s[j] = ‘*’ and update i = i + 1 and j = j – 1 then print the modified string.
• Repeat the above steps while j – i > 1.

Below is the implementation of the above approach:

C++

 // C++ program to print the required pattern #include using namespace std;    // Function to print the required pattern void printPattern(char s[], int n) {        // Print the unmodified string     cout << s << "\n";        // Reverse the string     int i = 0, j = n - 2;     while (i < j) {         char c = s[i];         s[i] = s[j];         s[j] = c;         i++;         j--;     }        // Replace the first and last character by '*' then     // second and second last character and so on     // until the string has characters remaining     i = 0;     j = n - 2;     while (j - i > 1) {         s[i] = s[j] = '*';         cout << s << "\n";         i++;         j--;     } }    // Driver code int main() {     char s[] = "geeks";     int n = sizeof(s) / sizeof(s);        printPattern(s, n);     return 0; }

Java

 // Java program to print the required pattern  class GFG {        // Function to print the required pattern  static void printPattern(char[] s, int n)  {      // Print the unmodified string      System.out.println(s);         // Reverse the string      int i = 0, j = n - 1;      while (i < j)      {          char c = s[i];          s[i] = s[j];          s[j] = c;          i++;          j--;      }         // Replace the first and last character      // by '*' then second and second last      // character and so on until the string     // has characters remaining      i = 0;      j = n - 1;      while (j - i > 1)      {          s[i] = s[j] = '*';          System.out.println(s);         i++;          j--;      }  }     // Driver Code public static void main(String []args) {     char[] s = "geeks".toCharArray();      int n = s.length;         printPattern(s, n); } }    // This code is contributed by Rituraj Jain

Python3

 # Python3 program to print the required pattern     # Function to print the required pattern  def printPattern(s, n):         # Print the unmodified string      print(''.join(s))        # Reverse the string      i, j = 0, n - 1            while i < j:          s[i], s[j] = s[j], s[i]          i += 1         j -= 1            # Replace the first and last character      # by '*' then second and second last      # character and so on until the string     # has characters remaining      i, j = 0, n - 1            while j - i > 1:          s[i], s[j] = '*', '*'         print(''.join(s))          i += 1         j -= 1    # Driver code  if __name__ == "__main__":        s = "geeks"     n = len(s)        printPattern(list(s), n)         # This code is contributed # by Rituraj Jain

C#

 // C# program to print the required pattern  using System;    class GFG {        // Function to print the required pattern  static void printPattern(char[] s, int n)  {      // Print the unmodified string      Console.WriteLine(s);         // Reverse the string      int i = 0, j = n - 1;      while (i < j)      {          char c = s[i];          s[i] = s[j];          s[j] = c;          i++;          j--;      }         // Replace the first and last character      // by '*' then second and second last      // character and so on until the string     // has characters remaining      i = 0;      j = n - 1;      while (j - i > 1)      {          s[i] = s[j] = '*';          Console.WriteLine(s);         i++;          j--;      }  }     // Driver Code public static void Main(String []args) {     char[] s = "geeks".ToCharArray();      int n = s.Length;         printPattern(s, n); } }    // This code is contributed by 29AjayKumar

Output:

geeks
*kee*
**e**

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