reverseBits.js

////////////////////////////////////////////////Reverse Bits/////////////////////////////////////////////
// Reverse bits of a given 32 bits unsigned integer.
// Note:
// Note that in some languages, such as Java, there is no unsigned integer type. In this case, both input and output will
// be given as a signed integer type. They should not affect your implementation, as the integer's internal binary representation is the same, whether it is signed or unsigned.
// In Java, the compiler represents the signed integers using 2's complement notation. Therefore, in Example 2 above, the
// input represents the signed integer -3 and the output represents the signed integer -1073741825.
// Example 1:
// Input: n = 00000010100101000001111010011100
// Output:    964176192 (00111001011110000010100101000000)
// Explanation: The input binary string 00000010100101000001111010011100 represents the unsigned integer 43261596, so return
// 964176192 which its binary representation is 00111001011110000010100101000000.
// Example 2:
// Input: n = 11111111111111111111111111111101
// Output:   3221225471 (10111111111111111111111111111111)
// Explanation: The input binary string 11111111111111111111111111111101 represents the unsigned integer 4294967293, so return
// 3221225471 which its binary representation is 10111111111111111111111111111111.
// Constraints:
// The input must be a binary string of length 32
// Follow up: If this function is called many times, how would you optimize it?
/**
 * @param {number} n - a positive integer
 * @return {number} - a positive integer
 */
 const reverseBits = function(n) {
    const t = n.toString(2).split("");
    while(t.length < 32) t.unshift("0");
    return parseInt(t.reverse().join(""), 2);
};

// console.log(reverseBits(00000010100101000001111010011100));
// console.log(reverseBits(11111111111111111111111111111101));