C/C++ Program to Count set bits in an integer
Write an efficient program to count number of 1s in binary representation of an integer.
Examples :
Input : n = 6 Output : 2 Binary representation of 6 is 110 and has 2 set bits Input : n = 13 Output : 3 Binary representation of 11 is 1101 and has 3 set bits
Recommended: Please solve it on “PRACTICE ” first, before moving on to the solution.
1. Simple Method Loop through all bits in an integer, check if a bit is set and if it is then increment the set bit count. See below program.
C
#include <stdio.h> /* Function to get no of set bits in binary representation of positive integer n */unsigned int countSetBits(unsigned int n){ unsigned int count = 0; while (n) { count += n & 1; n >>= 1; } return count;} /* Program to test function countSetBits */int main(){ int i = 9; printf("%d", countSetBits(i)); return 0;} |
Output:
2
Recursive Approach :
C++
// Cpp implementation of recursive// approach to find the number// of set bits in binary representation// of positive integer n#include <bits/stdc++.h>using namespace std; // recursive function to count set bitsint countSetBits(int n){ // base case if (n == 0) return 0; else // if last bit set add 1 else add 0 return (n & 1) + countSetBits(n >> 1);} // driver codeint main(){ // get value from user int n = 9; // function calling cout << countSetBits(n); return 0;} // This code is contributed by Raj. |
Output:
2
Please refer complete article on Count set bits in an integer for more details!
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