Rules: Fill the grid with digits 1~5 (1~4 for the example). Additionally, exactly two squares in each row and column should be blackened. Numbers outside the grid indicate the total of cells between the blackened squares in the corresponding row/column.
Background: I met this puzzle type first time in 15th JPC (2006), see the original page. The page is my print out. Mostly I tried to solve example first, and figure out the rules, and note that. Probably the page was from 2008 or 2009. Because I used this type first time for OAPC 2. Also I made for several competitions, including 18th WPC. After OAPC 2, in 2009 or 2010 Croco added this puzzle to the Croco Puzzle List as Doppelblock. As mentioned in Puzzle Wiki, this type belongs to Naoki Inaba. But I’m not sure, because on his page this type is labeled 2008, but in 15th JPC it was 2006.
I gave the name to this puzzle because of the same reasons which were mentioned for previous JPC puzzles.
[Edit]: A variation of type was developed by Takeya Saikachi, Smashed Multiples.