### 问题描述

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?

### 分析

先将数字换成二进制形式，然后逆序再将二进制换成十进制即可

### 代码

```
class Solution {
public:
uint32_t reverseBits(uint32_t n) {
int arr[32]={0};
int i=0;
while(n) {
arr[i++] = n%2;
n/=2;
}
uint32_t r = 0;
for(i=0;i<32;i++) {
r = r*2 + arr[i];
}
return r;
}
};
```