:)

Good old for-loop and Java ☕️ Well there's the one-liner Python 🐍 too, sum([ str(i).count('1') for i in range(1, n) if '1' in str(i) ]) ☝🏾 assuming we are returning this line from a method that takes n as parameter 🤪

Oh boy.. #MyTwitterAnniversary

@timClicks is it too early? 😆

for the love of C++

Happy 4th anniversary 🎁🎊🎉 and thanks for keeping it fun and challenging 🥂

Python 🐍