Number Of 1 Bits Problem
Description
LeetCode Problem 191.
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:
1
2
3
Input: n = 00000000000000000000000000001011
Output: 3
Explanation: The input binary string 00000000000000000000000000001011 has a total of three '1' bits.
Example 2:
1
2
3
Input: n = 00000000000000000000000010000000
Output: 1
Explanation: The input binary string 00000000000000000000000010000000 has a total of one '1' bit.
Example 3:
1
2
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.
Sample C++ Code
1
2
3
4
5
6
7
8
9
10
11
class Solution {
public:
int hammingWeight(uint32_t n) {
int sum = 0;
while (n != 0) {
sum++;
n &= (n - 1);
}
return sum;
}
};