Program for Reversed String Pattern

Given string str as the input. The task is to print the pattern as shown in the example.

Examples:

Input : str = “geeks” 
Output :
g 
e e 
* s k 
Explanation :
In the first line, print the first character in the string. 
In the second line, print the next two characters in reverse order. 
In the third line there are not enough characters to print, so append *s and print the characters in reverse order.

Input: str = “orange” 
Output:
o 
a r 
e g n 

Approach:

• Initialize an empty list and a variable x with the value 1.
• Traverse through the input string str and append the characters to the list.
• If the length of the list is equal to the value of x then 
  1. Print the characters in the list in reverse order.
  2. Increment the value of x by 1.
  3. Empty the list
• If the length of the last printed character is not 0 and it is less than the value of x then append x-length(x) *s and print it in reverse order.

Implementation:

C++

#include<bits/stdc++.h>
using namespace std;

// method declared to print the pattern of
// the string passed as argument
void reverseString(string str)
    {
        // a temporary string to store the
        // value of each row of pattern
        string r = "";
        int x = 1;
        for (int i = 0 ; i < str.length(); i++)
        {
            // extracting each character and
            // adding it to the string r
            r = r + str[i];
            if (r.length() == x)
            {
                // loop to print the string r in reverse order
                for(int j = r.length() - 1; j >= 0; j--)
                    cout<<r.at(j) << " ";
                x += 1;
                r = "";
                cout<<endl;
            }
        }

        // condition checking to add the "*" if required
        if (r.length() < x && r.length() != 0)
        {
            // adding the number of "*" required in r
            for(int k = 1; k <= x - r.length(); k++)
                r = r + "*";

            // printing r in reverse order
            for(int j = r.length() - 1; j >= 0; j--)
                    cout << r.at(j) << " ";
        }
    }

// Driver Code
int main()
{
    // sample string to check the code
    string str = "geeks";

    // method calling
    reverseString(str);
}

// This code is contributed by Rajput-Ji

Java

class GFG
{
    // method declared to print the pattern of
    // the string passed as argument
    public static void reverseString(String str)
    {
        // a temporary string to store the
        // value of each row of pattern
        String r = "";
        int x = 1;
        for (int i = 0 ; i < str.length(); i++)
        {
            // extracting each character and
            // adding it to the string r
            r = r + str.charAt(i);
            if (r.length() == x)
            {
                // loop to print the string r in reverse order
                for(int j = r.length() - 1; j >= 0; j--)
                    System.out.print(r.charAt(j) + " ");
                x += 1;
                r = "";
                System.out.println();
            }
        }

        // condition checking to add the "*" if required
        if (r.length() < x && r.length() != 0)
        {
            // adding the number of "*" required in r
            for(int k = 1; k <= x - r.length(); k++)
                r = r + "*";

            // printing r in reverse order
            for(int j = r.length() - 1; j >= 0; j--)
                    System.out.print(r.charAt(j) + " ");
        }
    }

    // Driver Code
    public static void main(String args[])
    {
        // sample string to check the code
        String str = "geeks";

        // method calling
        reverseString(str);
    }
}

// This code is contributed by Animesh_Gupta

Python 3

# function to print the pattern
def reverseString(str):

    # initialize an empty list
    r = []

    # initialize the value of x as 1
    x = 1

    # traverse through all the characters of x
    for i in str:

        # append all the characters to the list
        r.append(i)

        # if the length of the list is x
        if len(r)== x:

            # print the list in reverse order
            print(*reversed(r))

            # increment the value of x
            x+= 1
            # empty the list
            r = []

    # if the list is not empty
    # length of the list is less than x
    if len(r)<x and len(r)!= 0:

        # print x-len(r) *s and the reversed list
        print('* ' * (x-len(r)), *reversed(r))

# get the input string
str = "geeks"

# calling the function to print the pattern
reverseString(str)

C#

using System;

class GFG
{
    // method declared to print the pattern of
    // the string passed as argument
    public static void reverseString(String str)
    {
        // a temporary string to store the
        // value of each row of pattern
        String r = "";
        int x = 1;
        for (int i = 0 ; i < str.Length; i++)
        {
            // extracting each character and
            // adding it to the string r
            r = r + str[i];
            if (r.Length == x)
            {
                // loop to print the string r in reverse order
                for(int j = r.Length - 1; j >= 0; j--)
                    Console.Write(r[j] + " ");
                x += 1;
                r = "";
                Console.WriteLine();
            }
        }

        // condition checking to add the "*" if required
        if (r.Length < x && r.Length != 0)
        {
            // adding the number of "*" required in r
            for(int k = 1; k <= x - r.Length; k++)
                r = r + "*";

            // printing r in reverse order
            for(int j = r.Length - 1; j >= 0; j--)
                    Console.Write(r[j] + " ");
        }
    }

    // Driver Code
    public static void Main(String []args)
    {
        // sample string to check the code
        String str = "geeks";

        // method calling
        reverseString(str);
    }
}

// This code is contributed by PrinciRaj1992

Javascript

<script>

// method declared to print the pattern of
// the string passed as argument
function reverseString(str) {
        // a temporary string to store the
        // value of each row of pattern
        var r = "";
        var x = 1;
        for (var i = 0 ; i < str.length; i++)
        {
            // extracting each character and
            // adding it to the string r
            r = r + str[i];
            if (r.length == x)
            {
                // loop to print the string r in reverse order
                for(var j = r.length - 1; j >= 0; j--)
                    document.write( r[j] + " ");
                x += 1;
                r = "";
                document.write("<br>");
            }
        }

        // condition checking to add the "*" if required
        if (r.length < x && r.length != 0)
        {
            // adding the number of "*" required in r
            for(var k = 1; k <= x - r.length; k++)
                r = r + "*";

            // printing r in reverse order
            for(var j = r.length - 1; j >= 0; j--)
                    document.write( r[j] + " ");
        }
    }

// Driver Code
// sample string to check the code
var str = "geeks";

// method calling
reverseString(str);


</script>

Output

g 
e e 
* s k 

Complexity Analysis:

• Time Complexity: O(N), where n is the length of the given string
• Auxiliary Space: O(N)