191. Number of 1 Bits

Giới thiệu bài toán

Chi tiết: https://leetcode.com/problems/number-of-1-bits/

Yêu cầu

Write a function that takes the binary representation of 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.

Follow up: If this function is called many times, how would you optimize it?

Giải quyết bài toán

C#

public class Solution {
    public int HammingWeight(uint n) {
        uint result = 0;
        while (n > 0) {
            result += n & 1;
            n = n >> 1;
        }
        return (int)result;
    }
}

TypeScript

function hammingWeight(n: number): number {
    var result = 0;
    while (n > 0) {
        result += n & 1;
        n = n >>> 1;
    }
    return result;
};

Tham khảo:

• C#
• TypeScript