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?
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | public boolean isPalindrome( int x) { int [] nums= new int [ 32 ]; int i= 0 ; if (x< 0 ) //负数或 最后一位为0(后半句不严谨,单独0是对称的) return false ; while (x/ 10 > 0 ){ nums[i]=x% 10 ; i++; x=x/ 10 ; } nums[i]=x% 10 ; int len= 0 ; for (i= 31 ;i>= 0 ;i--){ if (nums[i]> 0 ){ len=i; //数字位数 break ; } } for (i= 0 ;i<=len/ 2 ;i++){ if (nums[i]!=nums[len-i]) return false ; } return true ; } |
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