LeetCode 190. Reverse Bits

分析

难度 易

来源

https://leetcode.com/problems/reverse-bits/submissions/

题目

Reverse bits of a given 32 bits unsigned integer.

Example:

Input: 43261596

Output: 964176192

Explanation: 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?

解答

package LeetCode;

import java.util.Stack;

public class L190_ReverseBits {
    public int reverseBits(int n) {
        int result=0;
        for(int i=0;i<31;i++){
            result+=n&1;//取n最低位
            n>>>=1;
            result<<=1;//result=result<<1;左移，移动后原低位在前，高位在后
        }
        result+=n&1;//最后一个在反转后为个位，不右移；放在循环中则执行多次判断
        return result;
    }
    public static void main(String[] args){
        L190_ReverseBits l190=new L190_ReverseBits();
        int n=43261596;
        System.out.println(l190.reverseBits(n));
    }
}