Efron appeared in great spirits as he hit up the Griffith Park Haunted Hayride with Julianne Hough and former "Hairspray" co-star Brittany Snow ... as well as director Adam Shankman.
TMZ broke the story -- the 25-year old actor completed 2 rounds of treatment earlier this year to combat the cocaine problem that took over his life.
Julianne's brother Derek Hough snapped a pic with the group sharing hugs and smiles -- and posted it online afterward saying, "Great time last night with great friends."
You can't stop the beat.
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