Number of 1 Bits – Leetcode Solution

In this post, we are going to solve the 191. Number of 1 Bits problem of Leetcode. This problem 191. Number of 1 Bits is a Leetcode easy level problem. Let’s see the code, 191. Number of 1 Bits – Leetcode Solution.

Problem

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.

Now, let’s see the code of 191. Number of 1 Bits – Leetcode Solution.

Diameter of Binary Tree – Leetcode Solution

191. Number of 1 Bits – Solution in Java

public class Solution {
    // you need to treat n as an unsigned value
    public int hammingWeight(int n) {
        int count =0 ;
        while(n != 0){
            count++;
            n = (n & (n-1));
            
        }
        return count;
    }
}

191. Number of 1 Bits – Solution in C++

class Solution {
public:
    int hammingWeight(uint32_t n) {
        int count =0 ;
        while(n != 0){
            count++;
            n = (n & (n-1));
            
        }
        return count;
    }
};

191. Number of 1 Bits – Solution in Python

def hammingWeight(self, n):
    """
    :type n: int
    :rtype: int
    """
    c = 0
    while n:
        n &= n - 1
        c += 1
    return c

Note: This problem 191. Number of 1 Bits is generated by Leetcode but the solution is provided by CodingBroz. This tutorial is only for Educational and Learning purpose.

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