如何判断两个字符串是否互为回文？

问题描述

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.");
      }
    }
}

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;
    }
}

Python中讨巧解法

def isPalindrome(self, x: int) -> bool:
    return str(x)==str(x)[::-1]