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/*
Challenge 120
TASK #1 - Swap Odd/Even bits
Submitted by: Mohammad S Anwar
You are given a positive integer $N less than or equal to 255.
Write a script to swap the odd positioned bit with even positioned bit and
print the decimal equivalent of the new binary representation.
Example
Input: $N = 101
Output: 154
Binary representation of the given number is 01 10 01 01.
The new binary representation after the odd/even swap is 10 01 10 10.
The decimal equivalent of 10011010 is 154.
Input: $N = 18
Output: 33
Binary representation of the given number is 00 01 00 10.
The new binary representation after the odd/even swap is 00 10 00 01.
The decimal equivalent of 100001 is 33.
*/
import std.stdio;
import std.conv;
int swap_bits(int n) {
int result = 0;
int shift = 0;
while (n > 0) {
if ((n & 1) != 0) { result |= 2 << shift; }
if ((n & 2) != 0) { result |= 1 << shift; }
n >>= 2;
shift += 2;
}
return result;
}
void main(string[] args) {
int n = 0;
if (args.length == 2) n = to!int(args[1]);
writeln(swap_bits(n));
}
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