A simple program to count set bits in all numbers from 1 to n

// A simple program to count set bits
// in all numbers from 1 to n.
class GFG{
	// Returns count of set bits present
	// in all numbers from 1 to n
	static int countSetBits( int n)
	{
		// initialize the result
		int bitCount = 0;
		for (int i = 1; i <= n; i++)
			bitCount += countSetBitsUtil(i);
		return bitCount;
	}	
	// A utility function to count set bits
	// in a number x
	static int countSetBitsUtil( int x)
	{
		if (x <= 0)
			return 0;
		return (x % 2 == 0 ? 0 : 1) +
			countSetBitsUtil(x / 2);
	}
	// Driver program
	public static void main(String[] args)
	{
		int n = 4;
		System.out.print("Total set bit count is ");
		System.out.print(countSetBits(n));
	}
}
// This code is contributed by
// Smitha Dinesh Semwal