Timeline for Christmas light horror story!
Current License: CC BY-SA 3.0
7 events
| when toggle format | what | by | license | comment | |
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| Jan 1, 2017 at 11:43 | history | edited | Jaap Scherphuis | CC BY-SA 3.0 |
Improved clarity of last paragraph.
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| Jan 1, 2017 at 11:38 | comment | added | Jaap Scherphuis | @TheGreatEscaper: Your way is a bit cleaner. I didn't think of it that way because I was trying to reduce the total number of wrong lights, and the concept of "non-domino wrong lights" did not occur to me. I'll edit my last paragraph - I did not mean to imply that it is unsolvable because we can reduce ot to a single domino, only that all unsolvable positions can be reduced to one domino. | |
| Jan 1, 2017 at 11:28 | comment | added | TheGreatEscaper | Nice solution! Very similar to mine, except I considered any leftmost wrong light. This removes any cases; we know the two lights to the left of that light are correct, as are their surroundings. So we make the light one space away wrong, then we make the light next to both of them wrong, and then make that initial leftmost light right. We've reduced the number of non-domino wrong lights by 1 and created a domino which can now be moved away to let us repeat this process. Also, 0 pairs of adjacent wrong lights isn't odd, so we don't need to reduce bad cases to one domino to see impossibility. | |
| Jan 1, 2017 at 11:26 | history | edited | Jaap Scherphuis | CC BY-SA 3.0 |
typo fix
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| Jan 1, 2017 at 11:22 | vote | accept | TheGreatEscaper | ||
| Jan 1, 2017 at 11:20 | history | edited | Jaap Scherphuis | CC BY-SA 3.0 |
edited body
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| Jan 1, 2017 at 11:15 | history | answered | Jaap Scherphuis | CC BY-SA 3.0 |