I'd love to see a minimal C program or similar, implemented as a single function `int64 run_2048(int64 state, int input)`, which takes the current state and an

I'd love to see a minimal C program or similar, implemented as a single function `int64 run_2048(int64 state, int input)`, which takes the current state and an input (left, right, up, down), and returns the next state. Could be an interesting code golf exercise.