Recursion

AP Computer Science A· difficulty 3/5

public static String rev(String s) {
    if (s.length() <= 1) return s;
    return rev(s.substring(1)) + s.charAt(0);
}
System.out.println(rev("abcd"));

What is printed?

A
$dcba$
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B
$abc$
C
$abcd$
D
$dabc$

Explanation

Each call moves the first character to the end of the recursively reversed remainder.

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