7
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enter image description here

Ripple Effect (taken from Nikoli)

  • The areas divided by bold lines are called "rooms". Fill in all empty cells with numbers under the following rules.
  • Each room contains consecutive numbers starting from 1 (to $n$ where $n$ is the area of the room).
  • If a number is duplicated in a row or a column, the space between the duplicated numbers must be equal to or larger than the value of the number.
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5
  • $\begingroup$ Just to clarify: the "space between" means the number of cells between, not counting either end? So 1 2 1 is possible but 1 1 isn't? $\endgroup$ Sep 4 '19 at 8:09
  • $\begingroup$ @Randal'Thor that's correct $\endgroup$
    – athin
    Sep 4 '19 at 8:18
  • $\begingroup$ Is this your puzzle or from somewhere else? I just have the slightest inkling I’ve seen it somewhere… $\endgroup$
    – boboquack
    Sep 4 '19 at 9:29
  • $\begingroup$ @boboquack this is my own puzzle, if you had seen this before I guess a participant of a local competition KPK is sharing it. (So yeah, this is one of the puzzles the competition I authored.) $\endgroup$
    – athin
    Sep 4 '19 at 10:15
  • $\begingroup$ @athin Nice! __ $\endgroup$
    – boboquack
    Sep 4 '19 at 11:02
7
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Final solution

enter image description here

Step by step

  • First fill in the two single-cell rooms with 1. Consider the left-hand one of these, and the two-cell room near it. If 1 is on the right of that two-cell room, then 1 can't be anywhere in the tetromino between. So we fill that two-cell room with 1 2. Then there's only one possible place for 2 in that tetromino between.

    enter image description here

  • In the next zigzag tetromino to the left, we can see which cells must be 3,4 and which must be 1,2. In the triomino above, 2 can't be at the top. That tells us where the 1 and 2 are in that tetromino, and then we can fill in that whole triomino and the top left domino.

    enter image description here

  • Now it's easy to fill in the rest of the three half-filled tetrominoes, and some stray 2s and 3s around the place:

    enter image description here

  • And then the rest of the left-hand side:

    enter image description here

  • And the rest goes smoothly to the end. (Let me know if I should add more details here, but I've shown now how the deductions work, and once half the grid is filled the rest becomes relatively easy.)

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9
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enter image description here

I like this game. I hope this solution can help.

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5
  • $\begingroup$ You got the first :-) Nice first answer! $\endgroup$ Sep 4 '19 at 9:05
  • $\begingroup$ Thanks but I didn't provide step-by-step pictures like you did $\endgroup$
    – user62289
    Sep 4 '19 at 9:11
  • $\begingroup$ Could you put your solution in a spoiler block, please? $\endgroup$
    – boboquack
    Sep 4 '19 at 9:26
  • $\begingroup$ I'm going to accept @Randal'Thor solution as it is more comprehensive, but +1 for fast solving! :D $\endgroup$
    – athin
    Sep 4 '19 at 10:16
  • $\begingroup$ (sorry, "the" should be "there" in my first comment - too late to correct) $\endgroup$ Sep 4 '19 at 10:30
-1
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So I got a different answer than the accepted one, I assume that means I made a mistake somewhere. Can anyone help me spot it?

Wrong solution to the puzzle

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2
  • 2
    $\begingroup$ In the third row, the gap between the second 4 and the third 4 is just two. $\endgroup$
    – hexomino
    Sep 5 '19 at 14:58
  • $\begingroup$ Ah, thank you! I guess I will have to re-do it. $\endgroup$
    – mihomir
    Sep 5 '19 at 15:29

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