There is something wrong with my code as one the testcase in my assignment is coming out wrong, giving me runtime error when I submit the code online. That testcase could be any String. I believe that everything is fine with the code as I have checked it manually for many testcases.
HERE IS THE CODE
public static boolean isStringPalindrome(String input) {
if(input.length()==0 || input.length()==1)
return true;
int first = 0;
int last = input.length()-1;
if(input.charAt(first) != input.charAt(last))
return false;
String str="";
for(int i=first+1;i<last;i++){
str = str+input.charAt(i);
}
boolean sa = isStringPalindrome(str);
return sa;
}
Sample Input
racecar
Output
true
Sample Input
pablo
Output
false
Your code appears to be overly complicated for recursively testing if the String
is a palindrome. Something like,
public static boolean isStringPalindrome(String input) {
if (input == null) {
return false;
} else if (input.isEmpty() || input.length() == 1) {
return true;
}
int len = input.length() - 1;
return input.charAt(0) == input.charAt(len) //
&& isStringPalindrome(input.substring(1, len));
}
Is recursive without embedding a for
loop. Because if you can do that, you should do something like
public static boolean isStringPalindrome(String input) {
if (input == null) {
return false;
} else if (input.isEmpty() || input.length() == 1) {
return true;
}
int len = input.length();
for (int i = 0; i <= len / 2; i++) {
if (input.charAt(i) != input.charAt(len - 1 - i)) {
return false;
}
}
return true;
}
A simpler way to check for palindrome can be:
public static boolean isPalindrome(String s)
{ if (input == null)
return false;
else if(s.length() == 0 || s.length() == 1)
return true;
/* check for first and last char of String:
* if they are same then do the same thing for a substring
* with first and last char removed. and carry on this
* until you string completes or condition fails.
*/
if(s.charAt(0) == s.charAt(s.length()-1))
return isPalindrome(s.substring(1, s.length()-1));
return false;
}
Update
You are getting runtime error(NZEC)
which means non-zero exit code
. It means your program is ending unexpectedly. I don't see any reason except that your program doesn't have a null
check. Otherwise, I have gone through your code carefully, you are doing the same thing which I have suggested.
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