Snaky Loop (Regions) (373)

Locate a "snaky loop" in the grid; it goes through some number of cells orthogonally and comes back to itself. Each cell is used at most once by the loop. The loop must occupy more than four cells and may not touch itself, not even diagonally. (In other words, if two cells in the loop touch orthogonally, then they must be exactly one cell apart along the path of the loop, and if two cells in the loop touch diagonally, then they must be exactly two cells apart along the path of the loop.)
The number of loop-occupied cells in each boldly-outlined region is the same. It is permissible for the loop to enter a region more than once.

Reference: WPF (1)