回文，英文 palindrome，如果该字符串的反转与原始字符串相同，则该字符串称为回文字符串。
比如: radar、level、
Able was I ere I saw Elba
回文，英文 palindrome，如果该字符串的反转与原始字符串相同，则该字符串称为回文字符串。
比如: radar、level、
Able was I ere I saw Elba
反转字符串与原字符串比较
反转字符串或数字，并将反转的字符串或数字与原始值进行比较。
package com.yuzhou1su.RelearnJava.Util;
public class palindrome {
public static void main(String[] args) { String str = "level", reverseStr = ""; int strLength = str.length(); for (int i = (strLength - 1); i >=0; --i) { reverseStr = reverseStr + str.charAt(i); } if (str.toLowerCase().equals(reverseStr.toLowerCase())) { System.out.println(str + " is a Palindrome String."); } else { System.out.println(str + " is not a Palindrome String."); } }}
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输出结果：level is a Palindrome String.
双指针
先把字符串转换为字符串数组，然后分别从字符串分组的前后进行遍历字符串，前后对比。
package com.yuzhou1su.RelearnJava.Util;
public class palindrome {
public static void main(String[] args) { String str = "level"; char[] strArray = str.toCharArray(); if (isPalindrom(strArray)) { System.out.println(str + " is a Palindrome String."); } else { System.out.println(str + " is not a Palindrome String."); } } public static boolean isPalindrom(char[] word){ int i1 = 0; int i2 = word.length - 1; while (i2 > i1) { if (word[i1] != word[i2]) { return false; } ++i1; --i2; } return true; }}
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Python 中讨巧解法
def isPalindrome(self, x: int) -> bool: return str(x)==str(x)[::-1]
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