Answer:
public static boolean isReverse(String s1, String s2)
{
if (s1.length() == 0 && s2.length() == 0)
{
return true;
}
else if (s1.length() == 0 || s2.length() == 0)
{
return false;
} else
{
String s1first = s1.substring(0, 1);
String s2last = s2.substring(s2.length() - 1);
return s1first.equalsIgnoreCase(s2last) &&
isReverse(s1.substring(1), s2.substring(0, s2.length() - 1));
}
}
public static boolean isReverse(String s1, String s2)
{
if (s1.length() != s2.length()) {
return false; // not same length
} else if (s1.length() == 0 && s2.length() == 0) {
return true;
} else
{
s1 = s1.toLowerCase();
s2 = s2.toLowerCase();
return s1.charAt(0) == s2.charAt(s2.length() - 1) &&
isReverse(s1.substring(1, s1.length()),
s2.substring(0, s2.length() - 1));
}
}
public static boolean isReverse(String s1, String s2)
{
if (s1.length() == s2.length())
{
return isReverse(s1.toLowerCase(), 0, s2.toLowerCase(), s2.length() - 1);
} else {
return false;
// not same length
}
}
private static boolean isReverse(String s1, int i1, String s2, int i2)
{
if (i1 >= s1.length() && i2 < 0) {
return true;
} else {
return s1.charAt(i1) == s2.charAt(i2) &&
isReverse(s1, i1 + 1, s2, i2 - 1);
}
}
public static boolean isReverse(String s1, String s2)
{
return reverse(s1.toLowerCase()).equals(s2.toLowerCase());
}
private static String reverse(String s)
{
if (s.length() == 0) {
return s;
} else {
return reverse(s.substring(1)) + s.charAt(0);
}
}
Explanation:
