Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.
Example 1:
Input: 121 Output: true
Example 2:
Input: -121 Output: false Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.
Example 3:
Input: 10 Output: false Explanation: Reads 01 from right to left. Therefore it is not a palindrome.
Follow up:
Coud you solve it without converting the integer to a string?
【tips】
1. Originally wanted to use the stack:
Get the top element of the stack .top(); //This function does not pop the top element of the stack
Pop: .pop();
2.ArrayList
Add element: .add(val);
Get the length of the list: .size();
Get the element at the i-th position: .get(i);
class Solution { public boolean isPalindrome(int x) { if(x<0){ return false; } if(x==0){ return true; } ArrayList list = new ArrayList<Integer>(); int a; boolean flag=true; while(x!=0){ a=x%10; list.add(a); x=x/10; } int length=list.size(); for(int i=0,j=length-1;i<j;i++,j--){ if(list.get(i)!=list.get(j)){ flag=false; } } return flag; } }