This question is part of NeetCode150 series.
Problem Description
Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-231, 231 - 1], then return 0.
Assume the environment does not allow you to store 64-bit integers (signed or unsigned).
Solution
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
class Solution {
public int reverse(int n) {
int ans = 0;
//while N is not 0, get the last digit and add it to ans while checking that the current value does not overflow
while(n != 0){
//last digit
int d = n%10;
//chop off the last digit from N
n = n/10;
//if the current ans is more than MAX/10 or current ans is equal to MAX && last digit is more than the digit in MAX_VALUE, return 0
//similarly for min value
if(ans > Integer.MAX_VALUE/10 || (ans == Integer.MAX_VALUE/10 && d > Integer.MAX_VALUE%10)) return 0;
if(ans < Integer.MIN_VALUE/10 || (ans == Integer.MIN_VALUE/10 && d < Integer.MIN_VALUE%10)) return 0;
ans = (ans * 10) + d;
}
return ans;
}
}