flowingfog

偶尔刷题

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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;
}

 

 

posted on 2018-10-11 19:45 flowingfog 阅读(...) 评论(...) 编辑 收藏