# Switch Sign of a Number

We make use of bit manipulation to solve this problem. using a NOT operator.

In this coding question, we use the NOT operator to switch the sign of a number.

## Problem Statement

We need to write a program to switch the sign of a number.

``````Input: 10

Output: -10``````

## Intuition

We already know that 2’s complement of any number gives a negative number with the formula below.

## Formula

~x = (232 - x)

For example,

``````>if, x = 1
~x = -2

if, y = 10
~y = -11``````

So if you see the pattern, the number is negated and converted to 2’s complement.

``````    number  = 8
~number  = -9
----------------------------
~number + 1 = (-9 + 1) = -8
----------------------------``````

## Solutions

### Java

``````class SignChange {
static int switchSign(int number){
return ~number + 1;
}

public static void main( String args[] ) {
int number = 8;
System.out.println(switchSign(number));
}
}``````

### Python

``````def switchSign(number):
return ~number + 1

number = 8
print(switchSign(number))
``````

### JavaScript

``````const switchSign = number => {
return ~number + 1;
}

let number = 8;
console.log(switchSign(number));``````

### C++

``````#include <iostream>

using namespace std;

int main() {
int number = 8;
cout << (~number + 1);
return 0;
}``````

### TypeScript

``````export const switchSign = (n: number): number => {
return (~n + 1);
}

let n: number = 8;
console.log(switchSign(n));``````

## Complexity Analysis

### Time Complexity

We are not running a loop or scaling the inputs. The inputs never change. So the operation takes a single unit of time, which is `O(1)`.

### Space Complexity

We didn’t create an extra memory for this. So, the space complexity is `O(1)`.

Coding Interview QuestionsData Structures and AlgorithmsBit Manipulation

### Gopi Gorantala Twitter

Gopi is an engineering leader with 12+ of experience in full-stack development—a specialist in Java technology stack. He worked for multiple startups, the European govt, and FAANG in India and Europe.

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