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问题描述:
Write a function that takes an unsigned integer and return the number of '1' bits it has (also known as the Hamming weight).
Example 1:
Input: 00000000000000000000000000001011 Output: 3 Explanation: The input binary string00000000000000000000000000001011 has a total of three '1' bits.
Example 2:
Input: 00000000000000000000000010000000 Output: 1 Explanation: The input binary string 00000000000000000000000010000000 has a total of one '1' bit.Example 3:
Input: 11111111111111111111111111111101 Output: 31 Explanation: The input binary string 11111111111111111111111111111101 has a total of thirty one '1' bits.
代码为(uint32_t 是无符号32位整型):
class Solution {
public:
int hammingWeight(uint32_t n) {
int res = 0;
while(n > 0)
{
//1000 & 0111 = 0000,所以有 1 个 1
//1001 & 1000 = 1000,所以有 2 个 1
//1010 & 1001 = 1000,所以有 2 个 1
// 使得 n 的最低位的 1 变为 0
n = (n & (n - 1));
res++;
}
return res;
}
};