LeetCode 9. Palindrome Number（回文数）

Posted 2021-01-12 flowingfog

---

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?

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;
}