Q191. Number of 1 Bits
直达:https://leetcode.com/problems/number-of-1-bits/description/
Write a function that takes an unsigned integer and returns the number of ’1' bits it has (also known as theHamming weight).
For example, the 32-bit integer ’11' has binary representation00000000000000000000000000001011
, so the function should return 3.
Credits: Special thanks to@tsfor adding this problem and creating all test cases.
分析:
二进制中,n&(n-1)作用是将n的二进制表示中的最低位为1的改为0,每更改一次计数器+1,知道n=0停止。
C++代码
class Solution {
public:
int hammingWeight(uint32_t n) {
int res = 0;
while(n){
n &= n-1;
res++;
}
return res;
}
};
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