📜  高效地找到数字的奇偶性

📅  最后修改于: 2021-05-25 01:57:13             🧑  作者: Mango

给定整数N。任务是编写程序以查找给定数字的奇偶校验。
注意:数字奇偶校验用于定义数字中的置位总数(二进制表示形式为1位)是偶数还是奇数。如果一个数字的二进制表示形式中的置位总数为偶数,则该数字被称为具有偶数奇偶校验,否则,它将具有奇数奇偶校验。

例子

通过执行以下操作,可以有效地计算由32位表示的数字的奇偶校验。
假设给定数字为x,然后执行以下操作:

  • y = x ^(x >> 1)
  • y = y ^(y >> 2)
  • y = y ^(y >> 4)
  • y = y ^(y >> 8)
  • y = y ^(y >> 16)

现在,y中最右边的位将表示x的奇偶校验。如果最右边的位是1,则x将具有奇数奇偶校验,如果它是0,则x将具有偶数奇偶校验。
因此,为了提取y的最后一位,请对y与1进行按位与运算。

为什么这样做?

if(y&1==1)
    odd Parity
else
    even Parity

下面是上述方法的实现:

C++
// Program to find the parity of a given number
#include 
 
using namespace std;
 
// Function to find the parity
bool findParity(int x)
{
    int y = x ^ (x >> 1);
    y = y ^ (y >> 2);
    y = y ^ (y >> 4);
    y = y ^ (y >> 8);
    y = y ^ (y >> 16);
 
    // Rightmost bit of y holds the parity value
    // if (y&1) is 1 then parity is odd else even
    if (y & 1)
        return 1;
    return 0;
}
 
// Driver code
int main()
{
    (findParity(9)==0)?cout<<"Even Parity\n":
                            cout<<"Odd Parity\n";
     
    (findParity(13)==0)?cout<<"Even Parity\n":
                            cout<<"Odd Parity\n";
     
    return 0;
}


Java
// Program to find the
// parity of a given number
import java.io.*;
 
class GFG
{
 
// Function to find the parity
static boolean findParity(int x)
{
    int y = x ^ (x >> 1);
        y = y ^ (y >> 2);
        y = y ^ (y >> 4);
        y = y ^ (y >> 8);
        y = y ^ (y >> 16);
 
    // Rightmost bit of y holds
    // the parity value
    // if (y&1) is 1 then parity
    // is odd else even
    if ((y & 1) > 0)
        return true;
    return false;
}
 
// Driver code
public static void main (String[] args)
{
    if((findParity(9) == false))
        System.out.println("Even Parity");
    else
        System.out.println("Odd Parity");
     
    if(findParity(13) == false)
        System.out.println("Even Parity");
    else
        System.out.println("Odd Parity");
}
}
 
// This Code is Contributed by chandan_jnu.


Python3
# Program to find the
# parity of a given number
 
# Function to find the parity
def findParity(x):
    y = x ^ (x >> 1);
    y = y ^ (y >> 2);
    y = y ^ (y >> 4);
    y = y ^ (y >> 8);
    y = y ^ (y >> 16);
 
    # Rightmost bit of y holds
    # the parity value if (y&1)
    # is 1 then parity is odd
    # else even
    if (y & 1):
        return 1;
    return 0;
 
# Driver code
if(findParity(9) == 0):
    print("Even Parity");
else:
    print("Odd Parity\n");
 
if(findParity(13) == 0):
    print("Even Parity");
else:
    print("Odd Parity");
     
# This code is contributed by mits


C#
// Program to find the
// parity of a given number
using System;
 
class GFG
{
 
// Function to find the parity
static bool findParity(int x)
{
    int y = x ^ (x >> 1);
        y = y ^ (y >> 2);
        y = y ^ (y >> 4);
        y = y ^ (y >> 8);
        y = y ^ (y >> 16);
 
    // Rightmost bit of y holds
    // the parity value
    // if (y&1) is 1 then parity
    // is odd else even
    if ((y & 1) > 0)
        return true;
    return false;
}
 
// Driver code
public static void Main ()
{
    if((findParity(9) == false))
        Console.WriteLine("Even Parity");
    else
        Console.WriteLine("Odd Parity");
     
    if(findParity(13) == false)
        Console.WriteLine("Even Parity");
    else
        Console.WriteLine("Odd Parity");
}
}
 
// This Code is Contributed
// by chandan_jnu


PHP
> 1);
    $y = $y ^ ($y >> 2);
    $y = $y ^ ($y >> 4);
    $y = $y ^ ($y >> 8);
    $y = $y ^ ($y >> 16);
 
    // Rightmost bit of y holds
    // the parity value if (y&1)
    // is 1 then parity is odd
    // else even
    if ($y & 1)
        return 1;
    return 0;
}
 
// Driver code
(findParity(9) == 0) ?
 print("Even Parity\n"):
 print("Odd Parity\n");
 
(findParity(13) == 0) ?
print("Even Parity\n"):
print("Odd Parity\n");
     
// This Code is Contributed by mits
?>


输出:
Even Parity
Odd Parity

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