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June 19 Nightmare
Posted: Thu Jun 22, 2006 7:36 pm
by AZ Matt
June 19 Nightmare: Wow... I am stuck here:
Code: Select all
346 2346 8 1234 7 5 136 9 1234
9 5 24 6 128 234 1378 1478 123478
1 7 246 2348 9 234 3568 2458 2348
457 1249 1247 2459 3 8 1247 1247 6
78 24 3 24 6 1 9 78 5
4568 12469 1246 7 25 249 18 3 1248
2 8 167 135 4 367 1357 157 9
367 136 9 12358 1258 2367 4 1578 1378
347 134 5 1389 18 379 2 6 1378
I've tried colouring, forcing chains -- what am I missing?
I bet it is obvious...
Posted: Fri Jun 23, 2006 12:09 am
by Ruud
You are missing, not necessarily in this order:
4 Line-box interactions
1 Naked pair
2 Hidden pairs
1 X-Wing
1 XY-Wing
1 XYZ-Wing
2 Finned X-Wings
1 Finned Swordfish
2 Nishio steps
But maybe there are quicker ways to solve this puzzle. Some of our regular guests may be able to help you.
Welcome to the site and forum!
Ruud.
Posted: Fri Jun 23, 2006 6:02 am
by GreenLantern
From your starting grid, the following basic steps can be applied:
- Removing 24 from r4c7
- Naked Triple (178) in Box 6 => r4c8<>17, r6c9<>18
- Locked Candidate '3' in Box 1 => r1c479<>3
- Locked Candidate '1' in Box 6 => r127c7<>1
- Hidden Single '6' in Box 1 => r3c3=6
- Hidden Single '6' in Row 7 => r7c6=6
Code: Select all
+-------------------------+-------------------------+-------------------------+
| 34 234 8 | 124 7 5 | 6 9 124 |
| 9 5 24 | 6 128 234 | 378 1478 123478 |
| 1 7 6 | 2348 9 234 | 358 2458 2348 |
+-------------------------+-------------------------+-------------------------+
| 457 1249 1247 | 2459 3 8 | 17 24 6 |
| 78 24 3 | 24 6 1 | 9 78 5 |
| 4568 12469 124 | 7 25 249 | 18 3 24 |
+-------------------------+-------------------------+-------------------------+
| 2 8 17 | 135 4 6 | 357 157 9 |
| 367 136 9 | 12358 1258 237 | 4 1578 1378 |
| 347 134 5 | 1389 18 379 | 2 6 1378 |
+-------------------------+-------------------------+-------------------------+
From here, I applied the following steps to solve the puzzle:
- Multicoloring in 7's: r47c3,r4c7,r5c8 => r7c8<>7
- [r1c2]=2=[r2c3]=4=[r46c3]-4-[r5c2]-2-[r1c2] => r46c12<>4, r46c2<>2
- [r4c2]=9=[r4c4]-9-[r6c6]=9|1=[r6c3]-1-[r4c2] => r4c2<>1
- [r8c4]=8=[r4c4]-8-[r2c5]=8|2=[r8c6]-2-[r8c4] => r8c4<>2
- Multicoloring in 8's: r38c4,r9c59 => r3c9<>8
- [r9c9]=8=[r9c5]-8-[r2c5]=8=[r3c4]=3=[r23c6]-3-[r9c6]-7-[r9c9] => r9c9<>7
- [r4c1](-7-[r5c1])=5=[r6c1]=6=[r6c2]=1=[r46c3]-1-[r7c3]-7-[r89c1]=7=[r4c1] => r6c1=56
- [r4c3]=7=[r7c3]=1=[r89c2]-1-[r6c2]-6-[r6c1]-5-[r4c1]=5=[r4c4]=4=[r5c4]-4-[r5c2]-2-[r4c3] => r4c3<>2
- [r2c9]=7=[r8c9]-7-[r7c7]=7=[r7c3]-7-[r4c3]-4-[r4c8]-2-[r6c9]-4-[r2c9] => r2c9<>4
- [r6c3]=4=[r6c9]-4-[r1c9]=4=[r1c12]-4-[r2c3]-2-[r6c3] => r6c3<>2
- Unique Rectangle (34): r19c12 => r8c1<>7, r8c2<>1
- Coloring in 2's: r3c68,r4c48,r6c59,r8c56 => r4c8/r6c5/r8c6=2
Sheesh....
Posted: Fri Jun 23, 2006 3:44 pm
by AZ Matt
I don't know how I got the 24 as candidates in r4c7. That was it. Thanks.