(LeetCode OJ) Number of 1 Bits【191】

(LeetCode OJ) Number of 1 Bits【191】

191. Number of 1 Bits

QuestionTotal Accepted: 65438 Total Submissions: 172909 Difficulty: Easy

Write a function that takes an unsigned integer and returns the number of ’1' bits it has (also known as the Hamming weight).

For example, the 32-bit integer ’11' has binary representation 00000000000000000000000000001011, so the function should return 3.

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

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Hide Tags Bit Manipulation Hide Similar Problems (E) Reverse Bits (E) Power of Two

//思路理清楚：首先這個數是正整數，題目說的很清楚
//一定情況：那麼只要這個數不為0，他就有1
//每次循環減少一個二進制最左邊的1  ---》n=n&n-1
//比如有5個1，則循環5次（減少5次）
class Solution {
public:
    int hammingWeight(uint32_t n) {
        int cnt=0;
        
        while(n)
        {
            cnt++;
            n=n&n-1;//減少一個二進制中最左邊的1
        }
        return cnt;
    }
};