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191. number of 1 bits

admin 11月 12, 2020 0

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.

题意分析：
通过&运算来判断每一位是否为1。

方法一：

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class Solution {
public:
    int (uint32_t n) {
        int sum = 0;
        
        for (int i = 0;i < 32;i++) {
            uint32_t num = 1 << i;
            if (num > n)
                break;
            if ((n & num) > 0)
                sum++;
        }
        return sum;
    }
};

方法二：

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int (uint32_t n) {
int cant=0;
while(n){
    if(n&1){
        cant++;
    }
    n=n>>1;
}   
return cant;
}

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