Recursion

AP Computer Science A· difficulty 3/5

public static boolean isPal(String s) {
  if (s.length() <= 1) return true;
  if (s.charAt(0) != s.charAt(s.length() - 1)) return false;
  return isPal(s.substring(1, s.length() - 1));
}
// call: isPal("level")

What does it return?

A
$null$
B
$stack overflow$
C
$true$
check_circle
D
$false$

Explanation

Each recursive call peels matching outer characters; "level" is a palindrome.

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