Calvin Harris - Worst Day

                The entire song uses the same 4 chords throughout repeated..

These are the four chords:

e|----0-----0----0-----0----|
B|----0-----0----0-----0----|
G|----9-----8----11----10---|
D|----10----9----12----11---|
A|----10----9----12----11---|
E|----8-----7----10----9----|

I'm unsure of their names but it's pretty clear that you keep your hand in the same 
position and slide it up and down the frets..

You should be able to easily pick up their timing and strumming pattern by listening to 
the song..

Hope this is cool- Cheers! DR~