7. Reverse Integer

https://leetcode.com/problems/reverse-integer/

C++

class Solution {
public:
    int reverse(int x) {
        if (x < 0) {
            return -reverse(-x);
        }
        int val = 0;
        while (x > 0) {
            val = val * 10 + x % 10;
            x = x / 10;
        }
        return val;
    }
};

Go

func reverse(x int) int {
    if x < 0 {
        return -reverse(-x)
    }

    val := 0
    for x > 0 {
        val = val*10 + x%10
        x = x / 10
    }
    return val
}

JavaScript

/**
 * @param {number} x
 * @return {number}
 */
var reverse = function(x) {
  if (x < 0) {
    return -reverse(-x)
  }

  var val = 0
  while (x > 0) {
    val = val * 10 + x % 10
    x = x / 10 >> 0
  }
  return val
}

Python

class Solution(object):

    def reverse(self, x):
        """
        :type x: int
        :rtype: int
        """
        if x < 0:
            return -self.reverse(-x)
        val = 0
        while x > 0:
            val = val * 10 + x % 10
            x = x // 10
        return val