# Skeleton sudoku, the second

I've already set one skeleton Sudoku. Here's a rather harder one. (Nonetheless, it should be within the realms of what can be done by hand; I solved it manually myself to verify that there was only one solution. Actually, I got pretty good at solving these, because it took me something like 5 or 6 attempts to find a puzzle whose solution was unique, learning more each time about what sort of patterns would allow multiple solutions to exist…)

Here's the grid:

In case you can't see images: I shaded a1, b1, e1, d2, c3, e3, and c4.

And here are the rules (basically the same as before, but hopefully stated a bit more clearly):

• Following the grid lines, separate this puzzle into five contiguous regions of five squares each, and also place a digit from 0 to 4 inclusive in each square, so that:
• (Generalised) Sudoku property:
• Each horizontal row must contain one each of 0, 1, 2, 3, 4;
• Each vertical column must contain one each of 0, 1, 2, 3, 4;
• Each of your regions must contain one each of 0, 1, 2, 3, 4.