The Days by Avicii is in C at 125 beats per minute and runs 3:11 across 61 bars. It uses 10 chords — C, G, F6, Em7, Am7, F, Am, Gsus4, and a few more. The chord diagram changes as the song plays and the words light up as they are sung, so you can strum and sing along without reading ahead.
Want the melody line note by note? The Days guitar melody tab.