Given a number N. The task is to find the number of set bits in its binary representation using recursion.
Input : 21
Output : 3
21 represesnted as 10101 in binray representation
Input : 16
Output : 1
16 represesnted as 10000 in binray representation
- First, check the LSB of the number.
- If the LSB is 1, then we add 1 to our answer and divide the number by 2.
- If the LSB is 0, we add 0 to our answer and divide the number by 2.
- Then we recursively follow step (1) until the number is greater than 0.
Below is the implementation of the above approach :
# Python3 progarm to find number
# of set bist in a number
# Recursive function to find
# number of set bist in a number
# Base condition
if (n == 0):
# If Least signifiant bit is set
if((n & 1) == 1):
return 1 + CountSetBits(n >> 1);
# If Least signifiant bit is not set
return CountSetBits(n >> 1);
# Driver code
if __name__ == ‘__main__’:
n = 21;
# Function call
# This code is contributed by 29AjayKumar
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- Count pairs with Bitwise AND as ODD number
- Count pairs with Bitwise OR as Even number
- Count pairs with Bitwise XOR as ODD number
- Count total bits in a number
- Count unset bits of a number
- Count pairs with Bitwise-AND as even number
- Count pairs with Bitwise XOR as EVEN number
- Count pairs (A, B) such that A has X and B has Y number of set bits and A+B = C
- Count number of set bits in a range using bitset
- Program to count number of set bits in an (big) array
- Count number of bits to be flipped to convert A to B | Set-2
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Improved By : ihritik