## LeetCode_7. Reverse Integer

7. Reverse Integer

Easy

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

Note:

Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231, 231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

```package leetcode;

public class ReverseInteger {
@org.junit.Test
public void test() {
int number1 = 123;
int number2 = -123;
int number3 = 120;
ReverseInteger reverseInteger = new ReverseInteger();

System.out.println(reverseInteger.reverse(number1));
System.out.println(reverseInteger.reverse(number2));
System.out.println(reverseInteger.reverse(number3));
}

public int reverse(int x) {
int rev = 0;
while (x != 0) {
int pop = x % 10;
x /= 10;
if (rev > Integer.MAX_VALUE / 10 || (rev == Integer.MAX_VALUE / 10 && pop > 7)) {
return 0;
}
if (rev < Integer.MIN_VALUE / 10 || (rev == Integer.MIN_VALUE / 10 && pop < -8)) {
return 0;
}
rev = rev * 10 + pop;
}
return rev;
}
}
```