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