【位运算】将整数的二进制奇偶位互换

题目

将整数的二进制奇偶位互换

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给定你一个整数 n ，返回它的二进制奇偶位互换后表示的数。

示例 1:

输入: n = 6
输出: 9
解释:
6 的二进制表示: 00000000000000000000000000000110
奇偶位互换后: 00000000000000000000000000001001 表示为 9

示例 2:

输入: n = 0b01000000_00000000_00000000_00000000
输出: 0b10000000_00000000_00000000_00000000

解题

方法一：位运算

思路

代码

class Solution {
    public int swapOddAndEvenBits(int n) {
        int even = n & 0xAAAAAAAA;
        int odd = n & 0x55555555;
        return (even >> 1) ^ (odd << 1);
    }
}

import java.util.*;
import java.io.*;

public class Main {
    static final int A = 0b10101010101010101010101010101010;
    static final int B = 0b01010101010101010101010101010101;

    public static void main(String[] args) throws IOException {
        StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
        in.nextToken();
        int n = (int) in.nval;
        int evenBits = n & A;
        int oddBits = n & B;
        System.out.println((evenBits >> 1) ^ (oddBits << 1));
    }
}