FilesExpand file tree

 master

/

Palindrome.java

Copy path

Blame

More file actions

Blame

More file actions

Latest commit

 

History

History

History

50 lines (42 loc) · 1.38 KB

 master

/

Palindrome.java

Copy path

Top

File metadata and controls

• Code
• Blame

50 lines (42 loc) · 1.38 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

package Others;

class Palindrome {

private String reverseString(String x) { // *helper method

StringBuilder output = new StringBuilder(x);

return output.reverse().toString();

}

public boolean FirstWay(String x) { // *palindrome method, returns true if palindrome

if (x == null || x.length() <= 1)

return true;

return x.equalsIgnoreCase(reverseString(x));

}

public boolean SecondWay(String x) {

if (x.length() == 0 || x.length() == 1)

return true;

if (x.charAt(0) != x.charAt(x.length() - 1))

return false;

return SecondWay(x.substring(1, x.length() - 1));

}

/**

* This method ignores all non-alphanumeric characters and case runs in O(n)

* where n is the length of s

*

* @param s String to check

* @return true if s is palindrome else false

*/

public boolean isPalindrome(String s) {

s = s.toLowerCase().trim();

StringBuilder sb = new StringBuilder();

for (char c : s.toCharArray()) {

if (Character.isLetter(c) || Character.isDigit(c))

sb.append(c);

}

s = sb.toString();

int start = 0;

int end = s.length() - 1;

while (start <= end) {

if (s.charAt(start++) != s.charAt(end--))

return false;

}

return true;

}

}