两道题的解题思路一样，取模不断的拿个位数做累加，用long型防止越界。
7. Reverse Integer
题目：Given a 32-bit signed integer, reverse digits of an integer.
Example 1:
Input: 123
Output: 321
Example 2:
Input: -123
Output: -321
Example 3:
Input: 120
Output: 21
class Solution {
public int reverse(int x) {
long res = 0;
while (x != 0) {
res = 10 * res + x % 10;
x /= 10;
}
return (res > Integer.MAX_VALUE || res < Integer.MIN_VALUE)
? 0 : (int) res;
}
}
9. Palindrome Number
题目：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.
class Solution {
public boolean isPalindrome(int x) {
if(x < 0) return false;
int temp = x;
long res = 0;
while(temp != 0){
res = res * 10 + temp % 10;
temp /= 10;
}
if(res > Integer.MAX_VALUE || res < Integer.MIN_VALUE
|| (int)res != x){
return false;
}
return true;
}
}
