Leetcode:number of 1 Bits

Write a function that takes an unsigned integer and returns the number of ' 1 ' bits it has (also known as the Hamming weigh T).

For example, the 32-bit integer ' One ' 00000000000000000000000000001011 has a binary representation, so the function should return 3.

Analysis: Test instructions calculates the number of 1 in the 32-bit integer 2 binary representation.

The method is still very numerous and well understood:

1, the use of 2 mathematical characteristics of the system to

Class Solution {public:    int hammingweight (uint32_t n) {        int count=0;        while (n) {        if (n%2==1) count++;        N=N/2;        }        return count;    }};

2, each bit and 1 do and calculation, calculate not 0 of the number can be

Class Solution {public:    int hammingweight (uint32_t n) {        int count=0;        while (n) {        count+=n&1;        n>>=1;        }        return count;    }};

3. Each n& (n-1) can reduce the number of bits in N to 1

Class Solution {public:    int hammingweight (uint32_t n) {        int sum = 0;        while (n)        {            n &= (n-1);            ++sum;        }         return sum;    }};

　　

　　

Leetcode:number of 1 Bits