0191.go

// Source: https://leetcode.com/problems/number-of-1-bits
// Title: Number of 1 Bits
// Difficulty: Easy
// Author: Mu Yang <http://muyang.pro>

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Write a function that takes an unsigned integer and returns the number of '1' bits it has (also known as the Hamming weight).
//
// Note:
//
//   Note that in some languages, such as Java, there is no unsigned integer type. In this case, the input will be given as a signed integer type. It 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 3, the input represents the signed integer. -3.
//
// Example 1:
//
//   Input: n = 00000000000000000000000000001011
//   Output: 3
//   Explanation: The input binary string 00000000000000000000000000001011 has a total of three '1' bits.
//
// Example 2:
//
//   Input: n = 00000000000000000000000010000000
//   Output: 1
//   Explanation: The input binary string 00000000000000000000000010000000 has a total of one '1' bit.
//
// Example 3:
//
//   Input: n = 11111111111111111111111111111101
//   Output: 31
//   Explanation: The input binary string 11111111111111111111111111111101 has a total of thirty one '1' bits.
//
// Constraints:
//
//   The input must be a binary string of length 32.
//
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package main

func hammingWeight(num uint32) int {
	weight := uint32(0)
	for i := 0; i < 32; i++ {
		weight += num % 2
		num >>= 1
	}
	return int(weight)
}