Question 4
Question 4: Reverse Integer
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).
Example 1:
Input: x = 123
Output: 321
Constraints:
-231 <= x <= 231 – 1
Example 2:
Input: x = -123
Output: -321
Example 3:
Input: x = 120
Output: 21
Solution:
C++
Java
Python
C++
Run
#include <bits/stdc++.h>
using namespace std;
int reverse(int x) {
int reversed = 0;
while (x != 0) {
int pop = x % 10;
x /= 10;
if (reversed > INT_MAX / 10 || (reversed == INT_MAX / 10 && pop > 7)) {
return 0;
}
if (reversed < INT_MIN / 10 || (reversed == INT_MIN / 10 && pop < -8)) {
return 0;
}
reversed = reversed * 10 + pop;
}
return reversed;
}
int main() {
int x;
cout << "Enter an integer: ";
cin >> x;
int result = reverse(x);
cout << "Reversed integer: " << result << endl;
return 0;
}
Java
Run
import java.util.Scanner;
class Main {
public static int reverse(int x) {
int INT_MAX = (int)Math.pow(2, 31) - 1;
int INT_MIN = -(int)Math.pow(2, 31);
int reversed = 0;
while (x != 0) {
int pop = x % 10;
x /= 10;
if (reversed > INT_MAX / 10 || (reversed == INT_MAX / 10 && pop > 7)) {
return 0;
}
if (reversed < INT_MIN / 10 || (reversed == INT_MIN / 10 && pop < -8)) {
return 0;
}
reversed = reversed * 10 + pop;
}
return reversed;
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.print("Enter an integer: ");
int x = sc.nextInt();
int result = reverse(x);
System.out.println("Reversed integer: " + result);
}
}
Python
Run
def reverse(x):
INT_MAX = 2**31 - 1
INT_MIN = -2**31
reversed_num = 0
sign = 1 if x > 0 else -1
x = abs(x)
while x != 0:
pop = x % 10
x //= 10
if reversed_num > INT_MAX // 10 or (reversed_num == INT_MAX // 10 and pop > 7):
return 0
if reversed_num < INT_MIN // 10 or (reversed_num == INT_MIN // 10 and pop < -8):
return 0
reversed_num = reversed_num * 10 + pop
return sign * reversed_num
x = int(input("Enter an integer: "))
result = reverse(x)
print("Reversed integer:", result)
