20 Apr 2012
Sorry that I have been away for so long, avid readers. I have been preparing for the summer of programming contests (Google Code Jam, TopCoder Open and the Internet Puzzle Solving Contest).
Hopefully I should be back to my usual one-puzzle-per-weekday schedule. Let me know if there are any types of puzzle you would particularly like to see.
Split the grid into subrectangles, so that each subrectangle contains exactly one marked cell.
It is not allowed for four subrectangles to meet at a point.
This marked cell indicates how the dimensions of the subrectangle compare. If the subrectangle is longer than it is tall, the marked cell should be marked with a horizontal line, whereas if it is taller than it is long, it should be marked with a vertical line. Finally, if the subrectangle is square, the marked cell should be marked with a plus.
12 Apr 2012
Well it turns out my first version of Puzzle 32 had more than 1000 different solutions (thanks Prasanna for noticing). I have fixed it, and have verified that this one has only one solution, but I have made the puzzle substantially harder (or harder than I thought it was...). By the way, sorry that I have not been publishing much recently - I have been preparing for the Google Code Jam Qualification Round.
24 Mar 2012
22 Mar 2012
21 Mar 2012
20 Mar 2012
19 Mar 2012
16 Mar 2012
15 Mar 2012
Here is a Mochikoro. Note that there is one clue on each row, and one clue on each column, and the clues are the numbers 1 to 10, each occurring once. Note also, that there is 180 degree symmetry, and that the symmetrical pairs are 1-6, 2-7, 3-8, 4-9 and 5-10. Thought that was interesting. That's all.
13 Mar 2012
12 Mar 2012
8 Mar 2012
7 Mar 2012
3 Mar 2012
20 Feb 2012
Shade some squares and draw a continuous path through the rest of the squares so that:
- The path goes through each region exactly once.
- Any numbered cell contains exactly that number of squares on the path.
- No two shaded cells lie directly across a region border from each other.
17 Feb 2012
You are given a grid with numbers in some of the cells.
Shade some of the cells dark, the others remaining light such that:
- All orthogonally contiguous areas of light cells are rectangles with sides parallel to the sides of the grid.
- There are no 2 x 2 areas of dark cells
- You can get from any light cell to any other moving only through light cells which are adjacent orthogonally or diagonally.
Rules for Hashi:
- Join up the islands with bridges so that you can get from any island to any other island.
- Bridges may only go horizontally or vertically.
- Bridges may not cross each other.
- You can put up to two bridges between any adjacent pair of islands.
- Each island is numbered with the number of bridges which end at that island.
14 Feb 2012
13 Feb 2012
A new Nikoli type that I have not published before: Barns.
Draw a single loop through all of the cells of the grid, that does not cross itself outside of the shaded area, does not change direction inside the shaded area and does not cross any thick borders between cells.
10 Feb 2012
The grid is split up by thick borders into areas called 'rooms'. Shade some of the cells of the grid in such a way that:
- Each room has at least one shaded cell.
- Within each room, all shaded cells form one connected component.
- No wall between two rooms has shaded cells on both sides.
- Adjacent rooms have different numbers of shaded cells.
9 Feb 2012
8 Feb 2012
I've decided to call this a hard puzzle, as I don't think it can be solved without a bit of trial and error. If you disagree, let me know. I've never seen a 0-clue Heyawake before!
To celebrate having moved my blog from Twitter, I am starting a series of small but interesting puzzles. Being as the number of possibilities are much smaller on such a small grid, it is possible that they have appeared elsewhere. If so, I hastily apologise.
I thought I would try my hand at making a new Puzzle Type. This puzzle type is called “Guards”, and it is sort of a blend of the Nikoli puzzle types Akari and Kurodoku.
Mark some of the empty squares as walls (black squares) and some as guards (empty circles) so that:
1) No two walls are adjacent
2) No two guards can see each other. (Guards can see horizontally and vertically up to the nearest wall or the edge of the grid)
3) Every empty cell is visible to a guard.
4) All the non-wall cells are connected orthogonally.
5) Each labelled wall cell indicates the number of adjacent guards.
6) Each labelled guard cell indicates the number of cells (including the one it inhabits) that it can see.
Another Akari for you.
Rules are available here: http://en.wikipedia.org/wiki/Light_Up
Summary of the rules: put light bulbs in some of the squares so that all of the squares are lit, but no two light bulbs light each other. The black squares block light, and each number indicates the number of adjacent squares that contain light bulbs. (The light bulbs are semi-polarized in such a way that they only shine horizontally or vertically)
Welcome to my logic trove! I have decided to migrate my blog from Tumblr because it seems easier for readers to comment, and I am more familiar with the environment. I hope you enjoy the puzzles I post here. If there is anything you would particularly like to see, please let me know.