#include <iostream>
#include <string>

// Recursive function to print all subsequences of the given string
void printSubsequences(const std::string &str, int index, std::string current) {
    // Base case: If we've processed all characters of the string
    if (index == str.size()) {//imp
        // Print the current subsequence if it's not empty
        if (!current.empty()) {
            std::cout << current << std::endl;
        }
        return; // Return to explore other subsequences
    }

    // Recursively call to include the current character in the subsequence
    printSubsequences(str, index + 1, current + str[index]);

    // Recursively call to exclude the current character from the subsequence
    printSubsequences(str, index + 1, current);
}

int main() {
    std::string str = "abc"; // Input string
    printSubsequences(str, 0, ""); // Initial call with an empty current subsequence
    return 0;
}


/*

index == str.size()
so print only index value 3
and include and exclude one after one

How it Works Step-by-Step for "abc"
Start with an empty subsequence: printSubsequences("abc", 0, "").
Include 'a': printSubsequences("abc", 1, "a").
    Include 'b': printSubsequences("abc", 2, "ab").
        Include 'c': printSubsequences("abc", 3, "abc") → Print "abc".
        Exclude 'c': printSubsequences("abc", 3, "ab") → Print "ab".
    Exclude 'b': printSubsequences("abc", 2, "a").
        Include 'c': printSubsequences("abc", 3, "ac") → Print "ac".
        Exclude 'c': printSubsequences("abc", 3, "a") → Print "a".
Exclude 'a': printSubsequences("abc", 1, "").
    Include 'b': printSubsequences("abc", 2, "b").
        Include 'c': printSubsequences("abc", 3, "bc") → Print "bc".
        Exclude 'c': printSubsequences("abc", 3, "b") → Print "b".
    Exclude 'b': printSubsequences("abc", 2, "").
        Include 'c': printSubsequences("abc", 3, "c") → Print "c".
        Exclude 'c': printSubsequences("abc", 3, "") (empty, so nothing is printed).

*/