对palindrome的常用判断

判断String是否为palindrome：Two Pointers(left & right) 同时边扫边check 当前两边的char是否相同

code

 public boolean isValidPalindrome(String s){
         int l = 0;
         int r = s.length() - 1;
         while (l < r){
             if(s.charAt(l) != s.charAt(r)){
                 return false;
             }else{
                 l++;
                 r--;
             }
         }
         return true;
     }

判断number是否为palindrome：先reverse original number 变为reversed number ，再判断 original number == reversed number ？

code

     public boolean isPalindrome(int x) {
         // handle input is negative  like -121 or end with 0
         if (x < 0 || (x != 0 && x % 10 == 0)) return false;

         int temp = x;
         int reverseInt = 0;
         while (x != 0) {
             reverseInt = reverseInt * 10 + x % 10;
             x = x / 10;
         }
         return (reverseInt == temp);
     }