【leetcode】【190】Reverse Bits

一、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 as00111001011110000010100101000000).

Follow up:

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

二、问题分析

这是一道位操作的题目。注意题目给定的是 unsigned integer，对应到java里应该是 >>>.

三、Java AC代码

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