Rules: Locate a snake in the grid, whose head and tail are given, with touching itself only diagonally. The remaining cells should form nine separate areas (five for the example) with the sizes 1~9 each (1~5 for the example). Numbers in the grid indicate the size of the area including that cell.
Background: This is one of my inventions. I designed first time for IPST December’s Contest 2008. Then I used it in OAPC 2, Snake Variations Contest 2011, 24th HPC, and 18th WPC Finals. Also it appeared in WPC French Qualifier 2009.