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79 lines
2.3 KiB
C++
79 lines
2.3 KiB
C++
/**
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* @file
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* @brief Implementation to [count sets
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* bits](https://www.geeksforgeeks.org/count-set-bits-in-an-integer/) in an
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* integer.
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*
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* @details
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* We are given an integer number. Let’s say, number. The task is to first calculate the
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* binary digit of a number and then calculate the total set bits of a number.
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*
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* Set bits in a binary number is represented by 1. Whenever we calculate the binary number of an integer value
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* it is formed as the combination of 0’s and 1’s. So digit 1 is known as a set bit in computer terms.
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* Time Complexity :- O(log n)
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* Space complexity :- O(1)
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* @author [Swastika Gupta](https://github.com/swastyy)
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*/
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#include <cassert> /// for assert
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#include <iostream> /// for io operations
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#include <vector> /// for std::vector
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/**
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* @namespace bit_manipulation
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* @brief Bit manipulation algorithms
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*/
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namespace bit_manipulation {
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/**
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* @namespace bitCount
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* @brief Functions for the [count sets
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* bits](https://www.geeksforgeeks.org/count-set-bits-in-an-integer/)
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* implementation
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*/
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namespace bitCount {
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/**
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* @brief The main function implements set bit count
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* @param n is the number whose set bit will be counted
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* @returns the count of the number set bit in the binary representation of `n`
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*/
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std::uint64_t countSetBits(int n) {
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int count = 0; // "count" variable is used to count number of 1's in binary
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// representation of the number
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while (n != 0) {
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count += n & 1;
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n = n >> 1; // n=n/2
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}
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return count;
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}
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} // namespace bitCount
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} // namespace bit_manipulation
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/**
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* @brief Test implementations
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* @returns void
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*/
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static void test() {
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// n = 4 return 1
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assert(bit_manipulation::bitCount::countSetBits(4) == 1);
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// n = 6 return 2
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assert(bit_manipulation::bitCount::countSetBits(6) == 2);
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// n = 13 return 3
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assert(bit_manipulation::bitCount::countSetBits(13) == 3);
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// n = 9 return 2
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assert(bit_manipulation::bitCount::countSetBits(9) == 2);
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// n = 15 return 4
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assert(bit_manipulation::bitCount::countSetBits(15) == 4);
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// n = 25 return 3
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assert(bit_manipulation::bitCount::countSetBits(25) == 3);
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std::cout << "All test cases passed" << std::endl;
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}
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/**
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* @brief Main function
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* @returns 0 on exit
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*/
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int main() {
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test(); // run self-test implementations
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return 0;
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}
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