Uniqueness: some simple exercises

Advanced methods and approaches for solving Sudoku puzzles

Uniqueness: some simple exercises

Postby Carcul » Sat Dec 31, 2005 4:56 pm

In this post I present several puzzles that can be used as simple exercises by those who are studying Uniqueness for the first time and want to apply the more basic “versions” of this technique. The purpose of these exercises is to solve the grids using only Uniqueness (besides hidden and naked singles and pairs, but nothing beyond that).

Exercise 1:

Code: Select all
 *-----------------------*
 | 7 . . | . . . | . 1 9 |
 | 4 6 . | 1 9 . | . . . |
 | . . . | 6 8 2 | 7 . 4 |
 |-------+-------+-------|
 | . 9 . | . . . | . . 7 |
 | . . . | 3 . . | 4 . 5 |
 | . . 6 | 7 . . | . . . |
 |-------+-------+-------|
 | . . 1 | . . . | . . . |
 | 2 . . | . 7 4 | . . . |
 | . . . | 2 . . | 3 . . |
 *-----------------------*

Exercise 2:

Code: Select all
 *-----------------------*
 | 4 . 1 | . 6 . | . . . |
 | 3 . . | . . . | 2 . . |
 | . . . | . . . | 8 . . |
 |-------+-------+-------|
 | 1 5 . | 2 . . | . . . |
 | 6 . . | . . . | . 1 . |
 | . . . | 9 . . | . . . |
 |-------+-------+-------|
 | . 2 . | 7 . 8 | . . . |
 | . . . | . . . | . 4 3 |
 | . 7 . | . . . | . . . |
 *-----------------------*

Exercise 3:

Code: Select all
 *-----------------------*
 | . . . | . . . | 1 . 9 |
 | 4 . . | . 5 . | . . . |
 | . . . | . 2 . | 3 . . |
 |-------+-------+-------|
 | . . . | 1 . 9 | . . . |
 | 5 . . | . . 7 | . . . |
 | . . . | 3 . . | . . . |
 |-------+-------+-------|
 | . 1 3 | . . . | . . . |
 | . 8 . | . . . | . 4 . |
 | . . 9 | . . . | . 2 . |
 *-----------------------*

Exercise 4:

Code: Select all
 *-----------------------*
 | 9 3 6 | . . . | . 7 5 |
 | 8 7 5 | . . 3 | . . 1 |
 | 1 4 2 | 7 5 6 | 3 8 9 |
 |-------+-------+-------|
 | . . 7 | . . . | 8 . . |
 | 5 1 4 | 8 . 2 | 7 . 6 |
 | . 8 9 | . 7 . | . . . |
 |-------+-------+-------|
 | 4 . . | . . 7 | 9 . 3 |
 | . . . | . 4 . | . . 7 |
 | 7 9 . | 2 . 5 | . . 8 |
 *-----------------------*

Exercise 5:

Code: Select all
 *-----------------------*
 | . 7 8 | . . . | . 1 . |
 | 5 . . | . 4 . | . . . |
 | . . 6 | . 7 2 | . . . |
 |-------+-------+-------|
 | 8 5 . | . . . | . . . |
 | . . 4 | 5 . 7 | 9 . . |
 | . . . | . . . | . 6 4 |
 |-------+-------+-------|
 | . . . | 1 8 . | 2 . . |
 | . . . | . 6 . | . . 1 |
 | . 1 . | . . . | 3 5 . |
 *-----------------------*


Exercise 6:

Code: Select all
 *-----------------------*
 | 8 9 6 | . 4 . | . . . |
 | . . . | . . . | 7 . 2 |
 | . . . | 9 . . | . 6 . |
 |-------+-------+-------|
 | . 1 8 | . . 9 | . 2 4 |
 | 6 . . | 3 . . | . 8 . |
 | . 3 . | . 1 . | . . . |
 |-------+-------+-------|
 | . . . | 4 . . | 2 . . |
 | 3 . . | . . 6 | . . . |
 | . . 5 | . 3 . | . 1 . |
 *-----------------------*

Exercise 7 (2,+):

Code: Select all
 *-----------------------*
 | 3 . 1 | . . 5 | . . . |
 | . 2 . | 7 1 . | . . . |
 | . . 9 | 3 6 . | . 1 4 |
 |-------+-------+-------|
 | 7 1 8 | 5 3 . | 9 . 2 |
 | 6 . . | 2 9 1 | . . 8 |
 | 2 9 5 | . 8 7 | . . 1 |
 |-------+-------+-------|
 | 9 8 . | . 7 . | 1 . . |
 | 1 . . | . 5 3 | . 2 . |
 | . . . | 1 2 . | . . 6 |
 *-----------------------*

Exercise 8 (1,+++):

Code: Select all
 *-----------------------*
 | . . . | . 7 . | . 8 6 |
 | . 2 . | 5 . . | . . . |
 | . . . | . . . | . . . |
 |-------+-------+-------|
 | . . . | . 6 3 | . . 7 |
 | . 5 . | . . . | 3 . . |
 | . . . | . 1 . | . . . |
 |-------+-------+-------|
 | . . . | 4 . . | 2 5 . |
 | 6 . . | 2 . . | . . . |
 | 1 . . | . . . | . . . |
 *-----------------------*


Have fun.

Carcul
Last edited by Carcul on Fri Nov 17, 2006 6:49 am, edited 9 times in total.
Carcul
 
Posts: 724
Joined: 04 November 2005

Postby AndrewStuart » Sat Dec 31, 2005 6:56 pm

Good examples Carcul. I got the Type 1 and Type 4 in the second exercise but I'd put a stupid artifical limit on my algorithm which stopped me seeing all the URs in exercise 1. Wound't have found that in a month of sundays. Nice one
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Posts: 21
Joined: 28 December 2005

Postby Carcul » Sun Jan 01, 2006 10:43 pm

AndrewStuart wrote:Good examples Carcul.


Thanks.

Regards, Carcul
Carcul
 
Posts: 724
Joined: 04 November 2005


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