1+ package Algorithms .string ;
2+
3+ public class IsPalindrome_2014_1229 {
4+ /*
5+ SOLUTION 1: Iterator.
6+ */
7+ public boolean isPalindrome1 (String s ) {
8+ if (s ==null ) {
9+ return false ;
10+ }
11+
12+ int len =s .length ();
13+
14+ int left =0 ;
15+ int right =len -1 ;
16+
17+ String sNew =s .toLowerCase ();
18+
19+ while (left <right ) {
20+ // bug 1: forget a )
21+ while (left <right && !isNumChar (sNew .charAt (left ))) {
22+ left ++;
23+ }
24+
25+ while (left <right && !isNumChar (sNew .charAt (right ))) {
26+ right --;
27+ }
28+
29+ if (sNew .charAt (left ) !=sNew .charAt (right )) {
30+ return false ;
31+ }
32+
33+ left ++;
34+ right --;
35+ }
36+
37+ return true ;
38+ }
39+
40+ public boolean isNumChar (char c ) {
41+ if (c <='9' &&c >='0' ||c <='z' &&c >='a' ||c <='Z' &&c >='A' ) {
42+ return true ;
43+ }
44+
45+ return false ;
46+ }
47+
48+ /*
49+ SOLUTION 2: Iterator2.
50+ */
51+ public boolean isPalindrome (String s ) {
52+ if (s ==null ) {
53+ return false ;
54+ }
55+
56+ int len =s .length ();
57+
58+ int left =0 ;
59+ int right =len -1 ;
60+
61+ String sNew =s .toLowerCase ();
62+
63+ while (left <right ) {
64+ // bug 1: forget a )
65+ if (!Character .isLetterOrDigit (sNew .charAt (left ))) {
66+ left ++;
67+ // bug 2: Line 67: error: cannot find symbol: method isLetterOrDigital(char)
68+ }else if (!Character .isLetterOrDigit (sNew .charAt (right ))) {
69+ right --;
70+ }else if (sNew .charAt (left ) !=sNew .charAt (right )) {
71+ return false ;
72+ }else {
73+ left ++;
74+ right --;
75+ }
76+ }
77+
78+ return true ;
79+ }
80+ }
