Mind palace

some thoughts

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191. Number of 1 Bits

Posted on Edited on In Disqus:
Symbols count in article: 343 Reading time ≈ 1 mins.

常规数1法

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class Solution {
public:
    int hammingWeight(uint32_t n) {
        int res = 0;
        while (n > 0) {
            res += (n & 1);
            n >>= 1;
        }
        return res;
    }
};

翻转最后一个1法
这个比较通用，不受n正负的影响

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class Solution {
public:
    int hammingWeight(uint32_t n) {
        int res = 0;
        while (n > 0) {
            ++res;
            n &= (n - 1); // 把最低位的1变成0
        }
        return res;
    }
};