McNuggets problem: Difference between revisions
→{{header|R}}: Mostly syntax improvements.
ReeceGoding (talk | contribs) m (→{{header|R}}: Syntax highlighting.) |
ReeceGoding (talk | contribs) (→{{header|R}}: Mostly syntax improvements.) |
||
Line 1,677:
There are two natural approaches. The first is to generate all valid x, y, and z and then apply the function:
<lang rsplus>allInputs <- expand.grid(x = 0:(100 %/% 6), y = 0:(100 %/% 9), z = 0:(100 %/% 20))
mcNuggets <- do.call(function(x, y, z) 6 * x + 9 * y + 20 * z, allInputs)</lang>
The second is to find all of the valid 6x, 9y, and 20z, and then sum them:
<lang rsplus>mcNuggets2 <- rowSums(expand.grid(seq(0, 100, 6), seq(0, 100, 9), seq(0, 100, 20)))</lang>
Either way, we get identical results, as checked by:
<lang rsplus>all(mcNuggets == mcNuggets2)</lang>
For our final answer, note that our choice to remove values from the vector 0:100 means our outputs will already be sorted, unique, and no greater than 100.
<lang rsplus>results <- setdiff(0:100, mcNuggets)
cat("The non-McNuggets numbers that are no greater than 100 are:", results, "\nThe largest is", max(results), "\n")</lang>
Ultimately, this can be done in one line:
<lang rsplus>max(setdiff(0:100, rowSums(expand.grid(seq(0, 100, 6), seq(0, 100, 9), seq(0, 100, 20)))))</lang>
However, using seq without naming its arguments is considered bad practice. It works here, but breaking this code up is probably a better idea.
{{output}}
<pre>> all(mcNuggets == mcNuggets2)
[1] TRUE</pre>
<pre>The non-McNuggets numbers that are no greater than 100 are: 1 2 3 4 5 7 8 10 11 13 14 16 17 19 22 23 25 28 31 34 37 43
The largest is 43 </pre>
<pre>> max(setdiff(0:100, rowSums(expand.grid(seq(0, 100, 6), seq(0, 100, 9), seq(0, 100, 20)))))
[1] 43</pre>
| |||