LeetCode（47）-Reverse Bits

题目：

Reverse bits of a given 32 bits unsigned integer.

For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented in binary as 00111001011110000010100101000000).

Follow up:
If this function is called many times, how would you optimize it?

Related problem: Reverse Integer

思路：

• 题意：给定一个无符号数，把他的二进制位转换过来
• 考虑首先把原数字右移，然后得到右移的数字，赋值给新数字，然后左移动

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代码：

public class Solution {
    // you need treat n as an unsigned value
    public int reverseBits(int n) {
         int res = 0;
        for(int i = 0; i < 32; i++, n >>= 1){
            res = res << 1 | (n & 1);
        }
        return res;
    }
}