In A Week by Hozier is in G at 130 beats per minute and runs 5:10 across 107 bars. It uses 10 chords — G5, G, A5, Em, C, Bb, F, C7, 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? In A Week guitar melody tab.