The Matching Socks Pile

Socks come out of the dryer one at a time onto a pile. If the new sock matches the one on top — pair them and set them aside! 🧦

You get the socks in dryer order. Pile them with the pairing rule and print two things on one line: pairs <count> left <count>.

Example:

Input: socks = ["red", "blue", "blue", "red", "green"] Output: pairs 2 left 1

red pushes, blue pushes, the second blue matches the top and pairs off, red now matches the new top red and pairs off, green pushes alone — 2 pairs made, 1 sock (green) left on the pile.