Talk:Sum to 100
A 'sum' that can be shown but not expressed ?
Not sure that I have understood your third request. Something that can be 'shown' but not 'expressed' ? Sounds appeallingly ineffable and mysterious, but perhaps not entirely clear ...
Judging by your undo of my first suggestion, I guess that you are not simply looking for the first or lowest-valued integer than can't be expressed as a sum constructed in this way, but then I don't actually have any idea of what you are asking for. Perhaps some kind of example or concretisation might clarify ? Hout (talk) 01:42, 1 January 2017 (UTC)
- See the REXX's output to help understand what is required. I have changed the word first to lowest which is much clearer to what was intended (I knew what I meant, but it was somewhat unclear in this context). (Note that negative sums/integers are possible, these sums are just negative "versions" of the positive sums, so the requirement was worded to avoid looking for negative results.) Since the sums are integers (as there is no way to get a non-integer sum from additions and/or subtractions of decimal digits or whole numbers). I used the word "expressed" as it isn't necessary to have the expression "shown". The word "shown" (to me) seems to indicate to display, not necessarily to express (in this case, mathematically). To answer your question, yes, it is possible. Showing something doesn't mean that it is being expressed (in the sense that it is being understood). I believe it boils down to word choices. I was trying for a concise wording of the requirement without being unnecessarily wordy (or obtuse). It's a fine art. -- Gerard Schildberger (talk) 02:04, 1 January 2017 (UTC)
- I've also added a trailing phrase to the 3rd requirement that (I think) fits in more to what you originally addressed. -- Gerard Schildberger (talk) 02:09, 1 January 2017 (UTC)
- Would it be consistent with your meaning to replace the word 'sum' with 'integer' ? Also if you are looking for the lowest integer that is inexpressible in these terms, perhaps it would be helpful to give an example of a higher integer of this kind, and demonstrate/explain its inexpressibility within this system ? Hout (talk) 02:16, 1 January 2017 (UTC)
- I used the word sum because it was already used in the task's preamble and the word was also defined (in context). Introducing another word (integer) would, I think, just belabor the effort to have another version of the sum word. The next number (after 211) that can't be expressed within the rules is 219. Another example of a sum that can't be expressed is 5791. I'm not sure how to demonstrate/explain its inexpressibility other than to show (display) all the possible mathematical expressions that don't (can't) express the 5791 sum. This would be somewhat of a strange proof (and voluminous), but not unheard of. -- Gerard Schildberger (talk) 02:29, 1 January 2017 (UTC)
- FWIW my experience as a reader is that using the word 'sum' at that point certainly proved confusing at first reading, and even now feels distractingly odd. 211 is certainly a number – a member of the set of integers – but the point you are making about it seems to be precisely that it is not a sum (the result of an addition) within this system. Hout (talk) 02:38, 1 January 2017 (UTC)
- I'm not saying that 211 isn't an integer or a number --- just that it (the sum of 211) can't be expressed mathematically in the context of the rules for this puzzle as stated in the task's preamble. 211 is a sum (in particular, the lowest sum) of the set of sums that can't be expressed within the rules. -- Gerard Schildberger (talk) 02:56, 1 January 2017 (UTC)
- PS on the issue of an example; an existence proof would be fine – you could just give an example of a number like 5791, say that it can't be expressed by a sum that is restricted to these permutations of digits and signs, and ask for code that finds the lowest positive integer that shares this property. Hout (talk) 02:46, 1 January 2017 (UTC)
- That seems overly wordy just to ask for the lowest positive sum that can't be expressed (within the rules). In particular, the requirement was expressly worded to find that sum. However, I will add an example (i.e.: such as 5074). -- Gerard Schildberger (talk) 02:56, 1 January 2017 (UTC)
a discussion of the task's requirements and wording
This (first) section of comments was moved here to the talk page from the task's requirements. -- Gerard Schildberger (talk) 18:07, 11 July 2017 (UTC)
Note: If you allow/disallow negative first numbers you do get different results. If you allow negative first numbers, which you should according to the specification; then you get at least two targets with the same highest number of solutions: The positive and negative versions of the same target, only the positive one is between 0 to 123456789. The specification assumes there is only one positive target with the maximum number of solutions. It is worth looking for multiple targets with the same number of solutions, just in case there are more. This is especially true if you try the variants with different lists of digits. For example using the digits '987654321' and excluding a negative first number comes up with two distinct targets with the same maximum number of solutions, both of which happen to be positive. If you are playing with the asymetric version with out leading negative numbers of different lists of digits the sums with the highest number of solution may only be negative. In this case it is worth excluding the test to show only positive totals and put up with seeing duplicate +ve and -ve solutions.
Robin Murison
- Added signature of Robin Murison by Gerard Schildberger (talk) 18:07, 11 July 2017 (UTC)
extra credit
I had initially thought to add an extra credit solution for the largest sum (except for the obvious 123456789). I'm not sure it would be a worthwhile (optional) requirement, it could be pretty CPU intensive. -- Gerard Schildberger (talk) 04:21, 1 January 2017 (UTC)
- Seems fine as an additional task – I've just added it for Haskell and it doesn't seem to noticeably increase the interpreter run-time. Hout (talk) 00:29, 5 January 2017 (UTC)
- For interpreted languages, it may be problematic. Even so, I added an "extra credit" (optional) requirement. -- Gerard Schildberger (talk) 00:44, 5 January 2017 (UTC)
- I might not be optimistic with AppleScript, but JavaScript and GHCi (the Haskell interpreter that comes with the GHC compiler) both seem quite relaxed about it when run from inside a code editor. Of course the data types and algorithm will make a difference :-) Hout (talk) 01:01, 5 January 2017 (UTC)
- For performance note that it is not necessary to generate the strings to count the solutions. There are 2 * 3 ** (base-2) possible strings. In base 2 the maximum value is 1 the minimum value -1. 0 can not be generated so 66% of values can be represented. The number of possible strings increases exponentially with the base, so to stretch this task for extra credit we could ask what is the %age in base 64, or 60 if we want to be Babylonian, or why not more. I often read that we use base 10 because we have 10 fingers, is there any archeological evidence that the Babylonians were severely deformed? --Nigel Galloway (talk) 12:54, 25 February 2017 (UTC)
- I know you're kidding, and of course the Babylonians had ten fingers, but the assumption is that they realized base 60 would be an advantageous base and chose it with intention, rather than just going with the number of digits they were born with. I don't know of anyone else who independently adopted base 60, but base 10 was far from universal around the world; the Mayans used base 20, the Hawaiians base 12, some other Pacific Islanders base 4... --Markjreed (talk) 00:54, 25 March 2024 (UTC)
- Apparently there is indeed some archeological evidence that nearly all Babylonians had twelve finger knuckles on the back of each hand, as well as five digits on the other side. And, albeit less impressively, ancient Mayan skeletons show that both of their hands (also with five digits apiece) were also connected to the rest of them by so-called "wrists"... (IKUAKAT) --Petelomax (talk) 04:42, 25 March 2024 (UTC)
- For performance note that it is not necessary to generate the strings to count the solutions. There are 2 * 3 ** (base-2) possible strings. In base 2 the maximum value is 1 the minimum value -1. 0 can not be generated so 66% of values can be represented. The number of possible strings increases exponentially with the base, so to stretch this task for extra credit we could ask what is the %age in base 64, or 60 if we want to be Babylonian, or why not more. I often read that we use base 10 because we have 10 fingers, is there any archeological evidence that the Babylonians were severely deformed? --Nigel Galloway (talk) 12:54, 25 February 2017 (UTC)
complete list of solutions for 9
For those that are interested (or need a sanity check), the 46 solutions (for the sum of 9) are:
solution: 9 ◄───► -1+2+3+4+5+6+7-8-9
solution: 9 ◄───► -1+2+3-4+5-6-7+8+9
solution: 9 ◄───► -1+2+3-4-5+6+7-8+9
solution: 9 ◄───► -1+2+3-45+67-8-9
solution: 9 ◄───► -1+2+34+56+7-89
solution: 9 ◄───► -1+2-3+4+5-6+7-8+9
solution: 9 ◄───► -1+2-3+4-5+6+7+8-9
solution: 9 ◄───► -1+23+4+5+67-89
solution: 9 ◄───► -1+23+4-5-6-7-8+9
solution: 9 ◄───► -1+23-4+5-6-7+8-9
solution: 9 ◄───► -1+23-4-5+6+7-8-9
solution: 9 ◄───► -1-2+3+4+5+6-7-8+9
solution: 9 ◄───► -1-2+3+4+5-6+7+8-9
solution: 9 ◄───► -1-2+3-4-5-6+7+8+9
solution: 9 ◄───► -1-2+3-4-56+78-9
solution: 9 ◄───► -1-2-3+4-5+6-7+8+9
solution: 9 ◄───► -1-2-3+45-6-7-8-9
solution: 9 ◄───► -1-2-3-4+5+6+7-8+9
solution: 9 ◄───► -1-2-34+56+7-8-9
solution: 9 ◄───► -1-23+45-6-7-8+9
solution: 9 ◄───► -12+3-45-6+78-9
solution: 9 ◄───► -12+34+5+6-7-8-9
solution: 9 ◄───► -12+34+56-78+9
solution: 9 ◄───► -12-34+5+67-8-9
solution: 9 ◄───► 1+2+3+4-5-6-7+8+9
solution: 9 ◄───► 1+2+3-4+5-6+7-8+9
solution: 9 ◄───► 1+2+3-4-5+6+7+8-9
solution: 9 ◄───► 1+2-3+4+5+6-7-8+9
solution: 9 ◄───► 1+2-3+4+5-6+7+8-9
solution: 9 ◄───► 1+2-3-4-5-6+7+8+9
solution: 9 ◄───► 1+2-3-4-56+78-9
solution: 9 ◄───► 1+2-34-56+7+89
solution: 9 ◄───► 1+23+4-5-6-7+8-9
solution: 9 ◄───► 1+23-4+5-6+7-8-9
solution: 9 ◄───► 1+23-45+6+7+8+9
solution: 9 ◄───► 1-2+3+4+5+6-7+8-9
solution: 9 ◄───► 1-2+3-4-5+6-7+8+9
solution: 9 ◄───► 1-2-3+4+5-6-7+8+9
solution: 9 ◄───► 1-2-3+4-5+6+7-8+9
solution: 9 ◄───► 1-2-3-4+5+6+7+8-9
solution: 9 ◄───► 1-2-3-4-5-67+89
solution: 9 ◄───► 1-23+4+5-67+89
solution: 9 ◄───► 1-23+45-6-7+8-9
solution: 9 ◄───► 1-23-4+5+6+7+8+9
solution: 9 ◄───► 1-23-45-6-7+89
solution: 9 ◄───► 12-34-56+78+9
46 solutions found for 9
complete list of the number of solutions for zero ──► 300
For those that are interested in the density of solutions:
22 solutions found for 0 ──────────────────────
43 solutions found for 1 ───────────────────────────────────────────
18 solutions found for 2 ──────────────────
41 solutions found for 3 ─────────────────────────────────────────
18 solutions found for 4 ──────────────────
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24 solutions found for 6 ────────────────────────
39 solutions found for 7 ───────────────────────────────────────
18 solutions found for 8 ──────────────────
46 solutions found for 9 ──────────────────────────────────────────────
17 solutions found for 10 ─────────────────
38 solutions found for 11 ──────────────────────────────────────
27 solutions found for 12 ───────────────────────────
38 solutions found for 13 ──────────────────────────────────────
24 solutions found for 14 ────────────────────────
43 solutions found for 15 ───────────────────────────────────────────
18 solutions found for 16 ──────────────────
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23 solutions found for 18 ───────────────────────
37 solutions found for 19 ─────────────────────────────────────
23 solutions found for 20 ───────────────────────
43 solutions found for 21 ───────────────────────────────────────────
25 solutions found for 22 ─────────────────────────
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25 solutions found for 26 ─────────────────────────
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8 solutions found for 127 ────────
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10 solutions found for 136 ──────────
5 solutions found for 137 ─────
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9 solutions found for 143 ─────────
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9 solutions found for 148 ─────────
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10 solutions found for 150 ──────────
9 solutions found for 151 ─────────
6 solutions found for 152 ──────
13 solutions found for 153 ─────────────
9 solutions found for 154 ─────────
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5 solutions found for 167 ─────
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5 solutions found for 174 ─────
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1 solution found for 176 ─
6 solutions found for 177 ──────
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4 solutions found for 183 ────
3 solutions found for 184 ───
5 solutions found for 185 ─────
4 solutions found for 186 ────
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1 solution found for 191 ─
4 solutions found for 192 ────
2 solutions found for 193 ──
1 solution found for 194 ─
4 solutions found for 195 ────
1 solution found for 196 ─
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7 solutions found for 198 ───────
3 solutions found for 199 ───
3 solutions found for 200 ───
4 solutions found for 201 ────
2 solutions found for 202 ──
3 solutions found for 203 ───
2 solutions found for 204 ──
2 solutions found for 205 ──
2 solutions found for 206 ──
6 solutions found for 207 ──────
4 solutions found for 208 ────
1 solution found for 209 ─
5 solutions found for 210 ─────
no solutions found for 211
4 solutions found for 212 ────
1 solution found for 213 ─
3 solutions found for 214 ───
1 solution found for 215 ─
6 solutions found for 216 ──────
1 solution found for 217 ─
3 solutions found for 218 ───
no solutions found for 219
3 solutions found for 220 ───
no solutions found for 221
4 solutions found for 222 ────
1 solution found for 223 ─
4 solutions found for 224 ────
2 solutions found for 225 ──
5 solutions found for 226 ─────
no solutions found for 227
4 solutions found for 228 ────
no solutions found for 229
3 solutions found for 230 ───
2 solutions found for 231 ──
2 solutions found for 232 ──
no solutions found for 233
5 solutions found for 234 ─────
no solutions found for 235
3 solutions found for 236 ───
1 solution found for 237 ─
3 solutions found for 238 ───
no solutions found for 239
6 solutions found for 240 ──────
no solutions found for 241
5 solutions found for 242 ─────
3 solutions found for 243 ───
6 solutions found for 244 ──────
2 solutions found for 245 ──
5 solutions found for 246 ─────
no solutions found for 247
2 solutions found for 248 ──
3 solutions found for 249 ───
2 solutions found for 250 ──
2 solutions found for 251 ──
7 solutions found for 252 ───────
1 solution found for 253 ─
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2 solutions found for 255 ──
5 solutions found for 256 ─────
2 solutions found for 257 ──
7 solutions found for 258 ───────
1 solution found for 259 ─
4 solutions found for 260 ────
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1 solution found for 263 ─
4 solutions found for 264 ────
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5 solutions found for 267 ─────
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2 solutions found for 271 ──
1 solution found for 272 ─
3 solutions found for 273 ───
1 solution found for 274 ─
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no solutions found for 277
4 solutions found for 278 ────
3 solutions found for 279 ───
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2 solutions found for 282 ──
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no solutions found for 284
2 solutions found for 285 ──
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1 solution found for 289 ─
1 solution found for 290 ─
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1 solution found for 293 ─
3 solutions found for 294 ───
1 solution found for 295 ─
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2 solutions found for 297 ──
2 solutions found for 298 ──
2 solutions found for 299 ──
no solutions found for 300
sum of 9 has the maximum number of solutions: 46
sums of 211 219 221 227 229 233 235 239 241 247 277 284 286 287 300 have the minimum number of solutions: 0
a discussion of the task's requirements and wording
This (added) section of superscript comments was moved here to the talk page from the task's requirements (the task's preamble). I also changed the hard-to-read superscript text to be displayed as "regular" text). -- Gerard Schildberger (talk) 18:12, 11 July 2017 (UTC)
- Note: If you allow/disallow negative first numbers you do get different results. If you allow negative first numbers, which you should according to the specification; then you get at least two targets with the same highest number of solutions: The positive and negative versions of the same target, only the positive one is between 0 to 123456789. The specification assumes there is only one positive target with the maximum number of solutions. It is worth looking for multiple targets with the same number of solutions, just in case there are more. This is especially true if you try the variants with different lists of digits. For example using the digits '987654321' and excluding a negative first number comes up with two distinct targets with the same maximum number of solutions, both of which happen to be positive. If you are playing with the asymetric version with out leading negative numbers of different lists of digits the sums with the highest number of solution may only be negative. In this case it is worth excluding the test to show only positive totals and put up with seeing duplicate +ve and -ve solutions.
- Robin Murison
- Added signature of Robin Murison by Gerard Schildberger (talk) 18:12, 11 July 2017 (UTC)
Yes, a minus sign (-) is allowed before the first digit(s) This is specifically allowed from the 2nd sentence in the task's preamble, there is no if about it.
There is only one sum (you call it a target) that has a maximum. This wasn't assumed, it was determined by examination of all possible targets (which were non-negative sums), in part, to give programmers a priori information. The 2nd task requirement asks the sum which has the maximum number of solutions (from zero to infinity --- this excludes negative sums/targets). There is only one correct answer --- but you may assume there will be more than one solution, and if so, the wording will be changed. The task's preamble could've been worded as asking for sum(s); it was a word choice that I made when composing the task's requirements.
Note that negative sums (targets) are specifically excluded as per the task's description/requirements.
It is worth looking for multiple targets (and indeed, that is a requirement of this task) with the same --- or for that matter --- any number of solutions, this is a purpose of this task.
The use of the digit string of 987654321 isn't allowed, only the digit string of 123456789.
-- Gerard Schildberger (talk) 19:07, 11 July 2017 (UTC)