You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
53 lines
1.1 KiB
53 lines
1.1 KiB
package class31;
|
|
|
|
public class Problem_0125_ValidPalindrome {
|
|
|
|
// 忽略空格、忽略大小写 -> 是不是回文
|
|
// 数字不在忽略大小写的范围内
|
|
public static boolean isPalindrome(String s) {
|
|
if (s == null || s.length() == 0) {
|
|
return true;
|
|
}
|
|
char[] str = s.toCharArray();
|
|
int L = 0;
|
|
int R = str.length - 1;
|
|
while (L < R) {
|
|
// 英文（大小写） + 数字
|
|
if (validChar(str[L]) && validChar(str[R])) {
|
|
if (!equal(str[L], str[R])) {
|
|
return false;
|
|
}
|
|
L++;
|
|
R--;
|
|
} else {
|
|
L += validChar(str[L]) ? 0 : 1;
|
|
R -= validChar(str[R]) ? 0 : 1;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
public static boolean validChar(char c) {
|
|
return isLetter(c) || isNumber(c);
|
|
}
|
|
|
|
public static boolean equal(char c1, char c2) {
|
|
if (isNumber(c1) || isNumber(c2)) {
|
|
return c1 == c2;
|
|
}
|
|
// a A 32
|
|
// b B 32
|
|
// c C 32
|
|
return (c1 == c2) || (Math.max(c1, c2) - Math.min(c1, c2) == 32);
|
|
}
|
|
|
|
public static boolean isLetter(char c) {
|
|
return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
|
|
}
|
|
|
|
public static boolean isNumber(char c) {
|
|
return (c >= '0' && c <= '9');
|
|
}
|
|
|
|
}
|