Swap two nibbles in a byte
In this problem, we are given a byte (8 bits) and we need to swap its two nibbles. A nibble is a group of 4 bits. The goal is to interchange the positions of the first four bits with the last four bits.
Problem Statement:
Given an 8-bit number (byte), we need to swap its two nibbles and obtain the result.
Example:
Let's take the byte 175
(binary: 10101111
) as an example. The first nibble is
1010
and the second nibble is 1111
. We need to swap them to get 11111010
,
which is the result 250
.
(175) 10101111 4 (bit) 1010 1111 ↘ ↙ 1111 1010 Result (11111010) (250)
Pseudocode
swapNibbles(num):
// Get the first nibble (lower 4 bits)
firstNibble = num & 15 // 15 in binary: 00001111
// Get the second nibble (upper 4 bits)
secondNibble = (num & 240) >> 4 // 240 in binary: 11110000
// Swap the nibbles by combining them in reverse order
result = (firstNibble << 4) | secondNibble
return result
Algorithm Explanation
- Create a function
swapNibbles(num)
that takes an integernum
as input and returns an integer as output. - To get the first nibble, perform a bitwise AND operation between
num
and15
. This can be done by using the binary mask00001111
, where the lower 4 bits are set to 1 and the upper 4 bits are set to 0. This will extract the lower 4 bits of the number as the first nibble. - To get the second nibble, perform a bitwise AND operation between
num
and240
and then shift the result 4 positions to the right. The binary mask11110000
extracts the upper 4 bits of the number, and shifting it 4 positions to the right gives us the second nibble. - Now, we have the first nibble and the second nibble. To swap them, we shift the first nibble 4 positions to the
left (
firstNibble << 4
) and then combine it with the second nibble using the bitwise OR operation (|
). This gives us the final result with the nibbles swapped. - Return the result.
Code Solution
Here given code implementation process.
// C program
// Swap two nibbles in a byte
#include <stdio.h>
void swapNibbles(int num)
{
// ( num & 15 ) Get initial 4 bit set bits in number
// (( num & 15) << 4) this is moving initial 4 bits in left side [A]
// (( num & 240)) Get next 4 bit set bits in number
// (( num & 240) >> 4 ) moving next 4 bits in right side [B]
// A or B return swap version of 4 bits
int result = ((num & 15) << 4) | ((num & 240) >> 4 );
printf("\n Number : %d",num);
printf("\n Result : %d",result);
}
int main(int argc, char const *argv[])
{
// (175) 10101111
// 4 (bit) 1010 1111
// ↘ ↙
// 1111 1010
// Result (11111010) (250)
swapNibbles(175);
// (225) 11100001
// 4 (bit) 1110 0001
// ↘ ↙
// 0001 1110
// Result (00011110) (30)
swapNibbles(225);
// (2) 00000010
// 4 (bit) 0000 0010
// ↘ ↙
// 0010 0000
// Result (00100000) (32)
swapNibbles(2);
return 0;
}
Output
Number : 175
Result : 250
Number : 225
Result : 30
Number : 2
Result : 32
/*
Java program
Swap two nibbles in a byte
*/
public class BitSwap
{
// Interchange 4 bits of a number
public void swapNibbles(int num)
{
// ( num & 15 ) Get initial 4 bit set bits in number
// (( num & 15) << 4) this is moving initial 4 bits in left side [A]
// (( num & 240)) Get next 4 bit set bits in number
// (( num & 240) >> 4 ) moving next 4 bits in right side [B]
// A or B return swap version of 4 bits
int result = ((num & 15) << 4) | ((num & 240) >> 4);
System.out.print("\n Number : " + num);
System.out.print("\n Result : " + result);
}
public static void main(String[] args)
{
BitSwap task = new BitSwap();
// (175) 10101111
// 4 (bit) 1010 1111
// ↘ ↙
// 1111 1010
// Result (11111010) (250)
task.swapNibbles(175);
// (225) 11100001
// 4 (bit) 1110 0001
// ↘ ↙
// 0001 1110
// Result (00011110) (30)
task.swapNibbles(225);
// (2) 00000010
// 4 (bit) 0000 0010
// ↘ ↙
// 0010 0000
// Result (00100000) (32)
task.swapNibbles(2);
}
}
Output
Number : 175
Result : 250
Number : 225
Result : 30
Number : 2
Result : 32
// Include header file
#include <iostream>
using namespace std;
/*
C++ program
Swap two nibbles in a byte
*/
class BitSwap
{
public:
// Interchange 4 bits of a number
void swapNibbles(int num)
{
// ( num &15 ) Get initial 4 bit set bits in number
// (( num &15) << 4) this is moving initial 4 bits in left side [A]
// (( num &240)) Get next 4 bit set bits in number
// (( num &240) >> 4 ) moving next 4 bits in right side [B]
// A or B return swap version of 4 bits
int result = ((num &15) << 4) | ((num &240) >> 4);
cout << "\n Number : " << num;
cout << "\n Result : " << result;
}
};
int main()
{
BitSwap task = BitSwap();
// (175) 10101111
// 4 (bit) 1010 1111
// ↘ ↙
// 1111 1010
// Result (11111010) (250)
task.swapNibbles(175);
// (225) 11100001
// 4 (bit) 1110 0001
// ↘ ↙
// 0001 1110
// Result (00011110) (30)
task.swapNibbles(225);
// (2) 00000010
// 4 (bit) 0000 0010
// ↘ ↙
// 0010 0000
// Result (00100000) (32)
task.swapNibbles(2);
return 0;
}
Output
Number : 175
Result : 250
Number : 225
Result : 30
Number : 2
Result : 32
// Include namespace system
using System;
/*
C# program
Swap two nibbles in a byte
*/
public class BitSwap
{
// Interchange 4 bits of a number
public void swapNibbles(int num)
{
// ( num & 15 ) Get initial 4 bit set bits in number
// (( num & 15) << 4) this is moving initial 4 bits in left side [A]
// (( num & 240)) Get next 4 bit set bits in number
// (( num & 240) >> 4 ) moving next 4 bits in right side [B]
// A or B return swap version of 4 bits
int result = ((num & 15) << 4) | ((num & 240) >> 4);
Console.Write("\n Number : " + num);
Console.Write("\n Result : " + result);
}
public static void Main(String[] args)
{
BitSwap task = new BitSwap();
// (175) 10101111
// 4 (bit) 1010 1111
// ↘ ↙
// 1111 1010
// Result (11111010) (250)
task.swapNibbles(175);
// (225) 11100001
// 4 (bit) 1110 0001
// ↘ ↙
// 0001 1110
// Result (00011110) (30)
task.swapNibbles(225);
// (2) 00000010
// 4 (bit) 0000 0010
// ↘ ↙
// 0010 0000
// Result (00100000) (32)
task.swapNibbles(2);
}
}
Output
Number : 175
Result : 250
Number : 225
Result : 30
Number : 2
Result : 32
<?php
/*
Php program
Swap two nibbles in a byte
*/
class BitSwap
{
// Interchange 4 bits of a number
public function swapNibbles($num)
{
// ( num & 15 ) Get initial 4 bit set bits in number
// (( num & 15) << 4) this is moving initial 4 bits in left side [A]
// (( num & 240)) Get next 4 bit set bits in number
// (( num & 240) >> 4 ) moving next 4 bits in right side [B]
// A or B return swap version of 4 bits
$result = (($num & 15) << 4) | (($num & 240) >> 4);
echo "\n Number : ". $num;
echo "\n Result : ". $result;
}
}
function main()
{
$task = new BitSwap();
// (175) 10101111
// 4 (bit) 1010 1111
// ↘ ↙
// 1111 1010
// Result (11111010) (250)
$task->swapNibbles(175);
// (225) 11100001
// 4 (bit) 1110 0001
// ↘ ↙
// 0001 1110
// Result (00011110) (30)
$task->swapNibbles(225);
// (2) 00000010
// 4 (bit) 0000 0010
// ↘ ↙
// 0010 0000
// Result (00100000) (32)
$task->swapNibbles(2);
}
main();
Output
Number : 175
Result : 250
Number : 225
Result : 30
Number : 2
Result : 32
/*
Node Js program
Swap two nibbles in a byte
*/
class BitSwap
{
// Interchange 4 bits of a number
swapNibbles(num)
{
// ( num & 15 ) Get initial 4 bit set bits in number
// (( num & 15) << 4) this is moving initial 4 bits in left side [A]
// (( num & 240)) Get next 4 bit set bits in number
// (( num & 240) >> 4 ) moving next 4 bits in right side [B]
// A or B return swap version of 4 bits
var result = ((num & 15) << 4) | ((num & 240) >> 4);
process.stdout.write("\n Number : " + num);
process.stdout.write("\n Result : " + result);
}
}
function main()
{
var task = new BitSwap();
// (175) 10101111
// 4 (bit) 1010 1111
// ↘ ↙
// 1111 1010
// Result (11111010) (250)
task.swapNibbles(175);
// (225) 11100001
// 4 (bit) 1110 0001
// ↘ ↙
// 0001 1110
// Result (00011110) (30)
task.swapNibbles(225);
// (2) 00000010
// 4 (bit) 0000 0010
// ↘ ↙
// 0010 0000
// Result (00100000) (32)
task.swapNibbles(2);
}
main();
Output
Number : 175
Result : 250
Number : 225
Result : 30
Number : 2
Result : 32
# Python 3 program
# Swap two nibbles in a byte
class BitSwap :
# Interchange 4 bits of a number
def swapNibbles(self, num) :
# ( num & 15 ) Get initial 4 bit set bits in number
# (( num & 15) << 4) this is moving initial 4 bits in left side [A]
# (( num & 240)) Get next 4 bit set bits in number
# (( num & 240) >> 4 ) moving next 4 bits in right side [B]
# A or B return swap version of 4 bits
result = ((num & 15) << 4) | ((num & 240) >> 4)
print("\n Number : ", num, end = "")
print("\n Result : ", result, end = "")
def main() :
task = BitSwap()
# (175) 10101111
# 4 (bit) 1010 1111
# ↘ ↙
# 1111 1010
# Result (11111010) (250)
task.swapNibbles(175)
# (225) 11100001
# 4 (bit) 1110 0001
# ↘ ↙
# 0001 1110
# Result (00011110) (30)
task.swapNibbles(225)
# (2) 00000010
# 4 (bit) 0000 0010
# ↘ ↙
# 0010 0000
# Result (00100000) (32)
task.swapNibbles(2)
if __name__ == "__main__": main()
Output
Number : 175
Result : 250
Number : 225
Result : 30
Number : 2
Result : 32
# Ruby program
# Swap two nibbles in a byte
class BitSwap
# Interchange 4 bits of a number
def swapNibbles(num)
# ( num & 15 ) Get initial 4 bit set bits in number
# (( num & 15) << 4) this is moving initial 4 bits in left side [A]
# (( num & 240)) Get next 4 bit set bits in number
# (( num & 240) >> 4 ) moving next 4 bits in right side [B]
# A or B return swap version of 4 bits
result = ((num & 15) << 4) | ((num & 240) >> 4)
print("\n Number : ", num)
print("\n Result : ", result)
end
end
def main()
task = BitSwap.new()
# (175) 10101111
# 4 (bit) 1010 1111
# ↘ ↙
# 1111 1010
# Result (11111010) (250)
task.swapNibbles(175)
# (225) 11100001
# 4 (bit) 1110 0001
# ↘ ↙
# 0001 1110
# Result (00011110) (30)
task.swapNibbles(225)
# (2) 00000010
# 4 (bit) 0000 0010
# ↘ ↙
# 0010 0000
# Result (00100000) (32)
task.swapNibbles(2)
end
main()
Output
Number : 175
Result : 250
Number : 225
Result : 30
Number : 2
Result : 32
/*
Scala program
Swap two nibbles in a byte
*/
class BitSwap
{
// Interchange 4 bits of a number
def swapNibbles(num: Int): Unit = {
// ( num & 15 ) Get initial 4 bit set bits in number
// (( num & 15) << 4) this is moving initial 4 bits in left side [A]
// (( num & 240)) Get next 4 bit set bits in number
// (( num & 240) >> 4 ) moving next 4 bits in right side [B]
// A or B return swap version of 4 bits
var result: Int = ((num & 15) << 4) | ((num & 240) >> 4);
print("\n Number : " + num);
print("\n Result : " + result);
}
}
object Main
{
def main(args: Array[String]): Unit = {
var task: BitSwap = new BitSwap();
// (175) 10101111
// 4 (bit) 1010 1111
// ↘ ↙
// 1111 1010
// Result (11111010) (250)
task.swapNibbles(175);
// (225) 11100001
// 4 (bit) 1110 0001
// ↘ ↙
// 0001 1110
// Result (00011110) (30)
task.swapNibbles(225);
// (2) 00000010
// 4 (bit) 0000 0010
// ↘ ↙
// 0010 0000
// Result (00100000) (32)
task.swapNibbles(2);
}
}
Output
Number : 175
Result : 250
Number : 225
Result : 30
Number : 2
Result : 32
/*
Swift 4 program
Swap two nibbles in a byte
*/
class BitSwap
{
// Interchange 4 bits of a number
func swapNibbles(_ num: Int)
{
// ( num & 15 ) Get initial 4 bit set bits in number
// (( num & 15) << 4) this is moving initial 4 bits in left side [A]
// (( num & 240)) Get next 4 bit set bits in number
// (( num & 240) >> 4 ) moving next 4 bits in right side [B]
// A or B return swap version of 4 bits
let result: Int = ((num & 15) << 4) | ((num & 240) >> 4);
print("\n Number : ", num, terminator: "");
print("\n Result : ", result, terminator: "");
}
}
func main()
{
let task: BitSwap = BitSwap();
// (175) 10101111
// 4 (bit) 1010 1111
// ↘ ↙
// 1111 1010
// Result (11111010) (250)
task.swapNibbles(175);
// (225) 11100001
// 4 (bit) 1110 0001
// ↘ ↙
// 0001 1110
// Result (00011110) (30)
task.swapNibbles(225);
// (2) 00000010
// 4 (bit) 0000 0010
// ↘ ↙
// 0010 0000
// Result (00100000) (32)
task.swapNibbles(2);
}
main();
Output
Number : 175
Result : 250
Number : 225
Result : 30
Number : 2
Result : 32
/*
Kotlin program
Swap two nibbles in a byte
*/
class BitSwap
{
// Interchange 4 bits of a number
fun swapNibbles(num: Int): Unit
{
// ( num & 15 ) Get initial 4 bit set bits in number
// (( num & 15) << 4) this is moving initial 4 bits in left side [A]
// (( num & 240)) Get next 4 bit set bits in number
// (( num & 240) >> 4 ) moving next 4 bits in right side [B]
// A or B return swap version of 4 bits
var result: Int = ((num and 15) shl 4) or((num and 240) shr 4);
print("\n Number : " + num);
print("\n Result : " + result);
}
}
fun main(args: Array < String > ): Unit
{
var task: BitSwap = BitSwap();
// (175) 10101111
// 4 (bit) 1010 1111
// ↘ ↙
// 1111 1010
// Result (11111010) (250)
task.swapNibbles(175);
// (225) 11100001
// 4 (bit) 1110 0001
// ↘ ↙
// 0001 1110
// Result (00011110) (30)
task.swapNibbles(225);
// (2) 00000010
// 4 (bit) 0000 0010
// ↘ ↙
// 0010 0000
// Result (00100000) (32)
task.swapNibbles(2);
}
Output
Number : 175
Result : 250
Number : 225
Result : 30
Number : 2
Result : 32
Time Complexity
The time complexity of this algorithm is O(1) because the operations involved (bitwise AND, OR, and shifting) are constant-time operations. The algorithm runs in constant time regardless of the size of the input (which is fixed at 8 bits in this case).
Output Explanation
The program takes three test cases: 175
, 225
, and 2
, and swaps the nibbles
for each of them.
- For
175
(binary:10101111
), the result is250
(binary:11111010
). The first nibble1010
is swapped with the second nibble1111
, giving us11111010
, which is250
in decimal. - For
225
(binary:11100001
), the result is30
(binary:00011110
). The first nibble1110
is swapped with the second nibble0001
, giving us00011110
, which is30
in decimal. - For
2
(binary:00000010
), the result is32
(binary:00100000
). The first nibble0000
is swapped with the second nibble0010
, giving us00100000
, which is32
in decimal.
The program successfully swaps the nibbles for each test case, and the output is as expected.
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