Palindrome Number

LeetCode原题：Palindrome Number

Determine whether an integer is a palindrome. Do this without extra space.

Spoilers：

Could negative integers be palindromes? (ie, -1)

If you are thinking of converting the integer to string, note the restriction of using extra space.

You could also try reversing an integer. However, if you have solved the problem "Reverse Integer", you know that the reversed integer might overflow. How would you handle such case?

There is a more generic way of solving this problem.

主要内容：判断给定整型数是否为回文数（即正序逆序均相同的数），返回判断结果（布尔值）。

解题思想：

1.得到给定整型数的长度n（/10），然后由0<=i<n/2，判断第1+i位上的数和第n-i位上的数是否相等来得出给定整型数是否是回文数。

2.负数不是回文数。

3.个位数为回文数

参考C代码：

int findNum(int x, int c) {
    int t1;
    int t2 = x;
    for(int i = 0; i < c; i++) {
        t1 = t2 % 10;
        t2 = t2 / 10;
        if(t2 == 0) break;
    }
    return t1;
}

bool isPalindrome(int x) {
    if(x < 0) return false;
    else if(x < 10) return true;
    else {
    int front, behind;
    int count1 = 0;
    int count2 = 0;
    int t = x;
    while(t != 0) {
        count1++;
        t = t / 10;
    }
    t = x;
    int c = count1 / 2;
    for (int i = 0; i < c; i++) {
        if(findNum(t, 1 + i) == findNum(t, count1 - i)) {
            count2++;
        }
    }
    if(count2 == c) return true;
    else return false;
    }
}