Question: Write an algorithm to print all possible combinations of characters in a string.

Answer: Any thoughts? One thing is for sure, we can definitely use some recursive logic here. Let’s approach this problem methodically. Since we need to generate combinations, we can start with a single character and then continue to add a character to combinations we have seen so far. Let’s use “abc” as an example.

Here’s some code in Java (for a change ) to achieve what we’ve described above.

void combine(String instr, StringBuffer outstr, int index)
{
    for (int i = index; i < instr.length(); i++)
    {
        outstr.append(instr.charAt(i));
        System.out.println(outstr);
        combine(instr, outstr, i + 1);
        outstr.deleteCharAt(outstr.length() - 1);
    }
} 

combine("abc", new StringBuffer(), 0);

Have a better solution? Please let us know through the comments section.

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4. Reverse the Order of Words in a String
5. Reverse a String