描述
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.
分析
常规题目，不过能学到一种bit操作的技巧，运算 n &= n-1 让 n 的最低位1反转，最后记录操作的次数即可。
解决方案1（Python）
常规做法，循环检查二进制位。
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| class Solution:
def hammingWeight(self, n: int) -> int:
result = sum(1 for i in range(32) if n & (1 << i))
return result
|
解决方案2（Python）
优化后的位运算。
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| class Solution:
def hammingWeight(self, n: int) -> int:
result = 0
while n:
n &= n-1
result += 1
return result
|
解决方案3(C++)
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| class Solution {
public:
int hammingWeight(uint32_t n) {
int count = 0;
int now = 0;
while(n) {
if(n & 1){
count++;
}
n = n>>1;
}
return count;
}
};
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一种bit操作的技巧。。。。每次运算 n &= n-1 让 n 的最低位1反转。
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| class Solution {
public:
int hammingWeight(uint32_t n) {
int count = 0;
while(n) {
n &= n-1;
count++;
}
return count;
}
};
|
解决方案4（Golang）
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| func hammingWeight(num uint32) int {
result := 0
var i uint32 = 0
for ; i < 32; i++ {
if 1 << i & num > 0 {
result++
}
}
return result
}
|
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