BM191NumberOf1Bits

Pre-defined Methods

• Integer.toBinaryString(int n) return binary string
• Integer.toBinaryString(int n).toCharArray() directly to array.

思路

• 知道可以用位运算，但是不会应用，参考discussion

https://discuss.leetcode.com/topic/57007/java-tle-question/2

Use string and array to do compare one by one. There is no unsigned problem.

Use %2 to get the bit. But cannot use for negtive. But learn about True Code, Complemental Code and Ones-complement Code

http://blog.csdn.net/onewalkingman/article/details/3746154

关于位运算

• >>右移，和>>>无符号右移的区别。

正数右移，高位用0补，负数右移，高位用1补，当负数使用无符号右移时，用0进行部位(自然而然的，就由负数变成了正数了)
http://blog.csdn.net/xiaochunyong/article/details/7748713