C++ Program to Reverse Bits of Number with Explanation
C++
Hard
Operators
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1 min read
179 words
This problem helps you practice core C++ fundamentals in a practical way. It builds intuition around binary, representation, reverse. Let’s break it down step by step so you can implement it confidently.
Problem Statement
Reverse the binary representation of a number.
Real Life: Used in network programming, cryptography.
Input Format
An integer N.
Output Format
Number obtained after reversing the binary representation of N.
Constraints
• N ≥ 0
• Use bitwise operations
• Ignore leading zeros
Concept Explanation
The number is first seen in binary.
Its bits are reversed, and the reversed bits are converted back to decimal.
This is useful in network programming and cryptography.
Step-by-Step Logic
1.Take the number N.
2.Initialize rev = 0.
3.While N > 0:
• Extract last bit: bit = N & 1.
• Shift rev left by 1.
• Add bit to rev.
• Shift N right by 1.
4.When loop ends, rev contains reversed binary value.
5.Print rev.
Code Solution
This explanation is written for learning purposes and to help beginners understand the concept clearly.
void operator_q14_reverse_bits() {
unsigned int num = 43; // Binary: 00000000000000000000000000101011
unsigned int result = 0;
for(int i = 0; i < 32; i++) {
result = result << 1; // Make space
result = result | (num & 1); // Add last bit of num
num = num >> 1; // Move to next bit
}
cout << "Original number: 43" << endl;
cout << "After reversing bits: " << result << endl;
}
Output Example
Output:
14
Number obtained after reversing the binary representation of N.
Common Mistakes
- Misreading input/output format.
- Not handling constraints and edge cases.
- Off-by-one errors in loops.
- Forgetting to reset variables between test cases (if any).
Solution Guide
Problem
Reverse the binary representation of a number.
Real Life: Used in network programming, cryptography.
Input / Output
Output
Number obtained after reversing the binary representation of N.
Constraints
• N ≥ 0
• Use bitwise operations
• Ignore leading zeros
Examples
Output:
14
Number obtained after reversing the binary representation of N.
Explanation
Concept Explanation
The number is first seen in binary.
Its bits are reversed, and the reversed bits are converted back to decimal.
This is useful in network programming and cryptography.
Step-by-Step Explanation
1.Take the number N.
2.Initialize rev = 0.
3.While N > 0:
• Extract last bit: bit = N & 1.
• Shift rev left by 1.
• Add bit to rev.
• Shift N right by 1.
4.When loop ends, rev contains reversed binary value.
5.Print rev.
Details
Common Mistakes
- Misreading input/output format.
- Not handling constraints and edge cases.
- Off-by-one errors in loops.
- Forgetting to reset variables between test cases (if any).
Official Solution
void operator_q14_reverse_bits() {
unsigned int num = 43; // Binary: 00000000000000000000000000101011
unsigned int result = 0;
for(int i = 0; i < 32; i++) {
result = result << 1; // Make space
result = result | (num & 1); // Add last bit of num
num = num >> 1; // Move to next bit
}
cout << "Original number: 43" << endl;
cout << "After reversing bits: " << result << endl;
}
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