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);
    }