Flipping Bits Problem

This problem asks the solver to print the flipped bits of 32bit unsigned integer.

In detail, you would be provided an integer -

9 (base 10)

You have to write a function such that it returns the 32 bit unsigned decimal integer result -

4294967286 (base 10)

All code would be in Javascript but you can use any language to solve this problem.

How one goes from 9 to 4294967286?

• first take the input and convert it a string using toString() function

 let s=n.toString(2);

• initialize a new variable and assign it to 32-(length of string)

 let temp=32-s.length;

Why temp is equal to 32-s.length - variable s stores the number in binary format i.e. n=9 in decimal and s would store "1001" in binary {datatype of s is string here}, you are asked in this case to generate a 32 bit integer so to add the remaining bits in s, we assign temp to the given formula.

• initialize a new variable and assign it to an empty string

let temp_s="";
for(let i=0;i<temp;i++)
    temp_s+="0";

temp_s appends 0 to an empty string of length temp.

• res_s would hold the string full of 0 and the converted string of the number in binary format

let res_s=temp_s+s; 

res_s=00000000000000000000000000001001

• flip_s would store the flipped string as 1 would convert to 0 and 0 to 1

let flip_s="";

• we use for of loop to traverse through string res_s

for(let i of res_s) {
        if(i==="0")
            flip_s+="1";
        else if(i==="1")
            flip_s+="0";
    }

Here every element in the string is checked for 0 and 1 and assigned to 1 and 0 respectively.

flip_s=11111111111111111111111111110110

• print the value of given expression on console/prompt screen

console.log( parseInt(flip_s, 2));

Here, parseInt() method converts the flip_s variable to decimal form and output results in

4294967286

This problem is the part of HackerRank's 1 Month Interview Prep Kit.

Comments

[Daniel Gonzalez]

Thank you! You gave me the main idea, and I ended up coding this, I think is easier to understand it like this.

function flippingBits(n) {
  const binaryString = n.toString(2).padStart(32, "0");
  const flippedString = binaryString
    .split("")
    .map((bit) => (bit === "0" ? "1" : "0"))
    .join("");
  const flippedNumber = parseInt(flippedString, 2);
  return flippedNumber;
}