7. Reverse Integer
Tags: ‘Math’
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.
Solution
5% 5%
public int reverse(int x) {
int result = 0;
System.out.println(Integer.MAX_VALUE);
System.out.println(Integer.MIN_VALUE);
System.out.println(-3 % 2); // -1
while (x != 0) {
int pop = x % 10; // pop the last digit
x /= 10;
if (result > Integer.MAX_VALUE/10 || (result == Integer.MAX_VALUE/10 && pop > 7)) return 0;
if (result < Integer.MIN_VALUE/10 || (result == Integer.MIN_VALUE/10 && pop < -8)) return 0;
result = result * 10 + pop;
}
return result;
}