Step by Step solution about How to resolve the algorithm Non-continuous subsequences step by step in the Java programming language

The provided Java code defines a class called NonContinuousSubsequences that generates and prints non-continuous subsequences of a given string. The algorithm uses a recursive function called seqR to explore all possible combinations of characters, separating them with spaces to create non-continuous subsequences.

Function Signature:

Parameters:

• s: The original string to generate subsequences from.
• c: A string to store the current subsequence being constructed.
• i: The index of the current character in the original string.
• added: The count of characters added to the current subsequence.

Recursive Algorithm:

The seqR function operates recursively to generate all possible non-continuous subsequences:

1. Base Case: If the index i reaches the end of the original string (s.length()), it means all characters have been processed. At this point, it checks if the current subsequence has more than the added count of characters (excluding spaces). If true, it prints the subsequence.

2. Recursive Steps:

   • With Character Added: It creates a new subsequence by appending the current character s.charAt(i) to c. Then, it recursively calls seqR with the updated index i + 1 and increments added by 1.
   • Without Character Added (Space): It creates a new subsequence by appending a space to c. Then, it recursively calls seqR with the updated index i + 1, but keeps added the same.

Example Usage:

In the main method:

This line calls the seqR function with the following parameters:

• s: The string "1234"
• c: An empty string
• i: 0 (the starting index of the string)
• added: 0 (the count of characters added initially)

The function will recursively generate and print all possible non-continuous subsequences of the string "1234". For example, the following subsequences may be printed:

• "1 "
• "1 2 "
• "1 2 3 "
• "1 2 3 4"
• "1 2 3 4" (with spaces in between characters)

Note that the output may vary depending on the order in which the recursive function generates the subsequences.

The provided Java code is a recursive algorithm that finds and prints non-continuous subsequences of a given string. The code maintains two parameters: c, which is the current subsequence being built, and added, which counts the number of non-space characters added to the subsequence.

The algorithm starts by checking if it has reached the end of the input string s. If so, it prints the current subsequence c if it contains at least one non-space character (indicated by the check c.trim().length() > added).

If the end of the string has not been reached, the algorithm recursively explores two possibilities:

1. Adding the current character from s (at index i) to the subsequence c and continuing the recursion with the next character in s.
2. Adding a space to the current subsequence c (to represent a gap) and continuing the recursion with the next character in s.

In the first case, the added parameter is incremented to indicate that a non-space character has been added to the subsequence. In the second case, added remains the same.

The algorithm continues this recursive exploration until all the characters in the input string have been processed.

For example, if s is "1234", the algorithm might generate the following non-continuous subsequences:

• "12"
• "1 2"
• "123"
• "1 2 3"
• "1234"
• "1 2 3 4"

public class NonContinuousSubsequences {

    public static void main(String args[]) {
        seqR("1234", "", 0, 0);
    }

    private static void seqR(String s, String c, int i, int added) {
        if (i == s.length()) {
            if (c.trim().length() > added)
                System.out.println(c);
        } else {
            seqR(s, c + s.charAt(i), i + 1, added + 1);
            seqR(s, c + ' ', i + 1, added);
        }
    }
}