計算整數的奇偶性

Problem

Compute the parity of a long integer.

Solution

- Erases the least significant bit of a number

e.g 1111 -> 1111 & 1110 = 1110 

     1110 -> 1110 & 1101 = 1100 

     1101 -> 1101 & 1100 = 1100 

     1100 -> 1100 & 1011 = 1000  

     1011 -> 1011 & 1010 = 1010

     1010 -> 1010 & 1001 = 1000 

using System;

namespace ComputerParity
{
    class Program
    {
        static bool IsOddParity(long num)
        {
            int count = 0;

            while (num != 0)
            {
                count ^= 1;
                num = num & (num - 1); 
            }

            return (count == 0) ? true : false; 

        }

        static void Main(string[] args)
        {
            for (long i = 0; i < 60; i++)
            {
                Console.WriteLine("{0} {1, 10}, {2, 10}", i.ToString("X10"), i, Program.IsOddParity(i));
            }
        }
    }
}

Output

0000000000          0,      False
0000000001          1,       True
0000000002          2,       True
0000000003          3,      False
0000000004          4,       True
0000000005          5,      False
0000000006          6,      False
0000000007          7,       True
0000000008          8,       True
0000000009          9,      False
000000000A         10,      False
000000000B         11,       True
000000000C         12,      False
000000000D         13,       True
000000000E         14,       True
000000000F         15,      False
0000000010         16,       True
0000000011         17,      False
0000000012         18,      False
0000000013         19,       True
0000000014         20,      False
0000000015         21,       True
0000000016         22,       True
0000000017         23,      False
0000000018         24,      False
0000000019         25,       True
000000001A         26,       True
000000001B         27,      False
000000001C         28,       True
000000001D         29,      False
000000001E         30,      False
000000001F         31,       True
0000000020         32,       True
0000000021         33,      False
0000000022         34,      False
0000000023         35,       True
0000000024         36,      False
0000000025         37,       True
0000000026         38,       True
0000000027         39,      False
0000000028         40,      False
0000000029         41,       True
000000002A         42,       True
000000002B         43,      False
000000002C         44,       True
000000002D         45,      False
000000002E         46,      False
000000002F         47,       True
0000000030         48,      False
0000000031         49,       True
0000000032         50,       True
0000000033         51,      False
0000000034         52,       True
0000000035         53,      False
0000000036         54,      False
0000000037         55,       True
0000000038         56,       True
0000000039         57,      False
000000003A         58,      False
000000003B         59,       True
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