Java: Restore the original string by entering the compressed string with this rule

Last update on May 13 2025 12:58:50 (UTC/GMT +8 hours)

Restore String from Compression Rule

When characters are consecutive in a string, it is possible to shorten it by replacing them with a certain rule. For example, the character string YYYYY, if it is expressed as # 5 Y, it is compressed by one character.
Write a Java program to restore the original string by entering the compressed string with this rule.
However, the # character does not appear in the restored character string.
Note: The original sentences are uppercase letters, lowercase letters, numbers, symbols, less than 100 letters, and consecutive letters are not more than 9 letters.

Input:
Multiple character strings are given. One string is given per line.
Output: The restored character string for each character on one line.

Visual Presentation:

Sample Solution:

Java Code:

// Importing the Scanner class from java.util package
import java.util.*;

// Main class named "Main"
public class Main {
    public static void main(String[] args) {
        // Creating a Scanner object to read input from the console
        Scanner stdIn = new Scanner(System.in);

        // Prompting the user to input the text
        System.out.println("Input the text:");

        // Reading the input string
        String str = stdIn.next();

        // Iterating through each character in the input string
        for (int i = 0; i < str.length(); ++i) {
            // Checking if the current character is '#'
            if (str.charAt(i) == '#') {
                // Repeating the next character by the specified number of times
                for (int j = 0; j < (str.charAt(i + 1) - '0'); ++j) {
                    // Printing the repeated character
                    System.out.print(str.charAt(i + 2));
                }
                // Skipping the processed characters (the count and the repeated character)
                i += 2;
            } else {
                // Printing the current character as it is
                System.out.print(str.charAt(i));
            }
        }
        // Printing a new line after processing the input string
        System.out.println();
    }
} 

Sample Output:

Input the text:
XY#6Z1#4023
XYZZZZZZ1000023

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Java program to restore a string from a compressed format where letters are followed by multi-digit counts.
• Write a Java program to decompress a string that uses nested compression rules.
• Write a Java program to restore a string from a compressed format that uses different symbols for various compression rules.
• Write a Java program to validate and decompress a string only if it strictly follows a specified compression rule.

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