# 函数部分

## lowbit函数

1（0001）
-1（1111）
1&（-1）=0001

## 判断最后一位

x&1; 可以取得x最后一位是1还是0

## 返回右起第一个1的位置

Returns one plus the index of the least significant 1-bit of x, or if x is zero, returns zero.

## 返回左起第一个1之前0的个数

Returns the number of leading 0-bits in x, starting at the most significant bit position. If x is 0, the result is undefined.

## 返回右起第一个1之后的0的个数

Returns the number of trailing 0-bits in x, starting at the least significant bit position. If x is 0, the result is undefined.

## 返回1的个数

Returns the number of 1-bits in x.

## 返回1的个数的奇偶性

Returns the parity of x, i.e. the number of 1-bits in x modulo 2.