# Mowing the Grass

## Context

After attempting to program in Grass for the entire morning, you decide to go outside and mow some real grass. The grass can be viewed as a string consisting exclusively of the following characters: wWv. w denotes tall grass which takes $$\ 1 \$$ unit of energy to mow. W denotes extremely tall grass which takes $$\ 2 \$$ units of energy to mow. Lastly v denotes short grass which does not need to be mowed.

You decide to mow the grass from left to right (beginning to the end of the string). However, every time you encouter a v (short grass), you stop to take a break to replenish your energy, before carrying on with the mowing. Your task is to calculate the maximum amount of energy expended while mowing. In other words, find the maximum total energy of mowing a patch of grass, that of which does not contain v.

### Example

In the example input below, the answer is $$\ 8 \$$. Although the patch wwwwwww is a longer patch of grass, it only costs $$\ 7 \$$ units of energy, whereas the optimal patch WWWW expends $$\ 2 \times 4 = 8 \$$ units of energy.

Input: WwwvWWWWvvwwwwwwwvWwWw
Output: 8


Here is an example Python program -> Try It Online!.

## Test Cases

WwwvWWWWvvwwwwwwwvWwWw -> 8
w -> 1
W -> 2
vwww -> 3
vWWW -> 6
v -> 0
vvvvvvv -> 0
vwvWvwvWv -> 2
vWWWWWWWWWWvwwwwwwwwwwwwwwwwwwwwwv -> 21
vWWWWWWWWWWvwwwwwwwwwwwwwwwwwwwv -> 20
vvWvv -> 2


This is , so the shortest code in bytes wins!

• @Shaggy Only the 3 characters I've mentioned are allowed, otherwise it may not look like grass :P May 7, 2020 at 20:14
• Mowing the Grass, to stop it from Growing the Mass!
– xnor
May 7, 2020 at 21:31
• As someone who has actually mowed quite a bit of grass in my life, I'd say this checks out. May 7, 2020 at 23:52
• Can anyone do it in Grass?
– user92069
May 8, 2020 at 0:42
• Hmm, v doesn't look much shorter than w. May 8, 2020 at 9:01

# Python 2, 49 bytes

lambda s:len(max(s.replace("W","ww").split('v')))


Try it online!

Here's how it works:

1. Replace each W with ww
2. Split on v's to produce chunks of consecutive w's
3. Take the max to get the longest one
4. Get its length

# Python 3.8, 55 46 44 bytes

Thanks @xnor for saving 2 bytes!
Thanks @dingledooper for saving 2 bytes!

lambda s,t=0:max((t:=c%2*t+c%5%3)for c in s)


Try it online!

A function that takes in a byte string, and returns the max energy.

Cool trick with eval.

## Python 2, 61 bytes

lambda s:max(eval("+".join(s+"v").replace("v","0,")))
w=1;W=2


Try it online!

Transforms the given string by adding + between characters, then replaces v with comma (e.g wWvW -> w+W+0,W).

• Wow, that is some crazy eval! For the 3.8 one, it looks like you can do stuff-~t for t+1+stuff, or directly express t:=t+[2,-t,1][ord(c)%3] since it happens the three chars are distinct mod 3.
– xnor
May 7, 2020 at 20:44
• @xnor Thanks! I was reluctant to go down the mod chain route, but it seems like everything lines up perfectly this time. May 7, 2020 at 21:14
• Oh wow, your mapping the mod to the value is super clean too.
– xnor
May 7, 2020 at 21:16
• Is it a default that we can accept a list of integers/bytes when it states "string"? May 8, 2020 at 1:01
• @JonathanAllan I'm not sure myself, but I've seen people done this before. I think this should be allowed, since Python bytes quacks like a string: gets printed like a string, and supports all string operations. Here is a demonstration. May 8, 2020 at 1:11

# Jelly,  9  8 bytes

O’%3ṣ0§Ṁ


Try it online!

### How?

O’%3ṣ0§Ṁ - Link: list of characters   e.g. "wwwvWvwWww"
O        - ordinals                        [119,119,119,118,87,118,119,87,119,119]
’       - decremented                     [118,118,118,117,86,117,118,86,118,118]
%3     - modulo three                    [1,1,1,0,2,0,1,2,1,1]
ṣ0   - split at zeros                  [[1,1,1],[2],[1,2,1,1]]
§  - sums                            [3,2,5]
Ṁ - maximum                         5

• Wow, works out perfectly with modulo May 8, 2020 at 8:20

# JavaScript (Node.js), 50 bytes

s=>Math.max(...Buffer(s).map(c=>e+=c%5%3||-e,e=0))


Try it online!

Or 42 bytes if we can take a Buffer (or an array of ASCII codes) as input:

s=>Math.max(...s.map(c=>e+=c%5%3||-e,e=0))


Try it online!

# K (oK), 1918 13 bytes

Solution:

|/+/'3!5!"v"\


Try it online!

Explanation:

Might be further golfable...

|/+/'3!5!"v"\ / the solution
"v"\ / split on "v"
5!     / modulo 5 (turns "vwW" into 3 4 2)
3!       / modulo 3 (turns 3 4 2 into 0 1 2)
+/'         / sum (+/) each (')
|/            / take maximum

• The split fails on the single char test cases. Perhaps you should do |/+/'3!5!"v"\(),. May 13, 2020 at 13:30
• I'd argue that "v" is a char and ,"v" is a string of length 1, which works :)
– mkst
May 13, 2020 at 20:01
• A fair point, indeed May 13, 2020 at 20:09

# Charcoal, 12 bytes

Ｉ⌈Ｅ⪪Ｓv⁺Ｌι№ιW


Try it online! Link is to verbose version of code. Explanation:

    Ｓ           Input string
⪪ v          Split on literal v
Ｅ             Map over chunks
ι     Current chunk
№ W    Count of literal W
⁺         Plus
Ｌι       Length of current chunk
⌈              Maximum
Ｉ               Cast to string for implicit print


# PowerShell 6+ for Windows, 48 bytes

port of math junkie's answer for Retina.

$args-creplace'W','ww'-split'v'|% len*|sort -b 1  Try it online! # Retina 0.8.2, 19 17 bytes -2 bytes thanks to @Neil! W ww S_v O^ \Gw  Try it online! Replaces W with ww, splits at v, sorts by length, then counts the w's in the largest chunk. • Nice; I've never needed to use S_ before. Tip: \Gw counts the number of ws at the beginning of the buffer. You can use this to help shave 2 bytes off your answer. – Neil May 7, 2020 at 20:39 • @Neil Cool tip, thanks! May 7, 2020 at 20:41 # J, 26 21 bytes [:>./0+/;.1@,3|2+3&u:  Try it online! • 3&u: Change input to unicode int values • 3|2+ Add 2 and then mod 3: Now v becomes 0, w becomes 1, and W 2. • 0..., Prepend 0 • +/;.1 Split by first element (0) and sum the elements of each split chunk • [:>./ Take the max # APL (Dyalog Unicode), 21 bytes (((⌈/+/¨)×⊆⊢)'vwW'∘⍳)  Try it online! Assumes IO is 0. How it works: • we convert v, w and W into 0, 1, 2 respectively; • we split on 0s; • we sum each run of non-zeroes; • and find the max of those. # Haskell, 51 45 bytes -6 bytes thanks to Ad Hoc Garf Hunter! Unfortunately all the grass-like operators were already taken :( g=maximum.scanl(#)0 x#'w'=x+1 x#'W'=x+2 x#_=0  Try it online! Explanation scanl is basically a "running total", where for each element of a list, it applies a function to the element and an accumulator, and saves the accumulator at each step. So scanl (+) 0 [1,2,3] gives [0,1,3,6]. We're giving it the function (#) which we've defined to add 1 to the accumulator if the element of the list is 'w', add 2 to the accumulator if it's 'W' or set the accumulator to 0 if it's anything else ('v'). Then we just get the maximum number of the new list, which will be the largest sum we managed to accumulate. Cool idea I couldn't get to work: mapping = zip "vwW" [(*0),(+1),(+2)] • Cheers @AdHocGarfHunter :) May 10, 2020 at 13:36 • We also don't require you to score the g= since maximum.scanl(#)0 is a function on its own. So if you would like to drop 2 bytes off you may. May 10, 2020 at 17:25 # Vyxal, 8 bytes \v/va›ṠG  Try it Online!  / # Split on \v # "v" v # For each a # Is each char uppercase? › # Increment Ṡ # Sum each G # Maximum  • @DLosc Good idea, having a look... May 29, 2021 at 23:12 • Yep, k[ does the trick. May 29, 2021 at 23:25 # Perl 5 + -p0166lF -MList::Util+max, 19 bytes $\=max$\,@F+y/W//}{ Try it online! ### Explanation -p reads STDIN into $_ breaking on each $/, -0166 sets $/ to v and -l strips $/ from the end of each $_, sets $\ to $/ and enables automatic printing of $\ at the end via print (because $_ will be empty outside of the loop and print outputs $\ at the end of each set of arguments - which default to $_ if none are passed). -F splits the input into an array of chars, stored in @F.

This stores the larger of $\ (initialised to v which is 0 when compared numerically) or @F (which is the array of chars in the input, or the length of the array when used in a numerical context) added to the number of W in the string. Since $\ is globally scoped, storing it here lasts for each iteration of the script the }{ breaks out of the while (<STDIN>) { loop that -p inserts and terminates it so that instead of the current value of $_ being printed alongside $\, $_ is empty and only $\ is printed.

# C (gcc), 69$$\\cdots\$$62 60 bytes

Saved 5 bytes thanks to Arnauld!!!
Saved 2 4 btes thanks to dingledooper!!!

e;m;f(char*g){for(e=m=0;*g;m=m>e?m:e)e=*g%2*e+*g++%5%3;e=m;}


Try it online!

# 05AB1E, 8 bytes

Ç<3%0¡Oà


Try it online!

# Ruby-naFv, 35 bytes

-naFv enables input on STDIN with auto-split on v into the $F global array. p$F.map{|w|w.gsub(?W){11}.size}.max


Try it online!

# Jelly, 9 bytes

ṣ”v<”w‘§Ṁ


Try it online!

# Explanation

ṣ”v<”w‘§Ṁ  Main Link
ṣ”v        Split on "v"
<”w     Check if less than "w" ("w" = 0, "W" = 1)
‘    Add one to every element
§   Sum every sublist
Ṁ  Find the maximum


# AWK, 85 82 69 bytes

{FS="v";gsub("W","ww");for(;i<NF;){s=length($++i);m=m>s?m:s;}print m}  Try it online! Thanks to @dingledooper for cutting off 13 bytes. The code could be even less, 62 bytes accounting for the field separator flag being a parameter and not part of the actual code. pretty straightforward: change all W into w, get lenght of words, v counts as field separator. Retain max score with ternary operator. • A couple basic golf ideas for 69 bytes May 9, 2020 at 5:45 • Thanks @dingledooper, very nice touch! I'm not familiar with the rules, but apparently I can put the -F"v" as argument and further reduce the total number of bytes. Is that a valid move? May 9, 2020 at 5:50 • Yes you are allowed to add arguments, just make sure you include it in the header. Personally, I rarely use flags, since it seems a bit of a "cheap" golf, but it's up to you :) May 9, 2020 at 5:56 # Java (JDK), 62 bytes s->{int m=0,n=0;for(var c:s)m=(n=c%2*n+c%5%3)>m?n:m;return m;}  Try it online! After finishing it, it seems to be a port of Noodle9's C answer. # C# (Visual C# Interactive Compiler), 69 bytes Func<string,int>g=s=>s.Replace("W","ww").Split('v').Max(x=>x.Length);  Try it online! Heavy inspiration from @xnor # Bash, 28 bytes sed 's,W,ww,g;y/v/\n/'|wc -L  Input from stdin, output to stdout There might be a better way. Try it online! # Mathematica, 53 bytes Max[#~(s=StringCount)~"W"+#~s~_&@StringSplit[#,"v"]]&  More readable, un-golfed code: Max[StringCount[#,"W"]+StringCount[#,_]&[StringSplit[#,"v"]]]&  StringSplit[#,"v"] takes a string and turns it into a list of strings, seperated by 'v', then add together the length of the string, and the count of 'W's, and take the max value. # Crystal, 57 bytes def f(a);a.split('v').max_of {|s|s.count('W')+s.size};end  Try it online! # Python 2, 70 bytes Comprehensive approach. lambda n:max([sum([2if i=="W"else 1for i in x])for x in n.split('v')])  Try it online! # Rust, 67 bytes Port of xnor's answer |s:&str|s.replace("W","ww").split('v').map(str::len).max().unwrap()  Try it online! # Stax, 14 bytes π├♦.8Σ0└ó?∟X≈Æ  Try it online! # Pip, 13 bytes MX#*YaR'Wt^'v  Try it online! ### Explanation  a First command-line argument R'W Replace all occurrences of W t with 10 (arbitrary value--the important thing is, it's two characters) ^'v Split on occurrences of v Y Yank (to enforce precedence) #* Replace each string in the list with its length MX Take the maximum  # Excel, 101 bytes =MAX(LEN(SUBSTITUTE(FILTERXML("<a><b>x"&SUBSTITUTE(A1,"v","</b><b>x")&"</b></a>","//b"),"W","ww"))-1)  Link to Spreadsheet • "<a><b>x"&SUBSTITUTE(A1,"v","</b><b>x")&"</b></a>" converts text to XML containing "x" + the "wW" strings. The additional "x" prevents errors. • FILTERXML(~,"//b") converts XML to a vertical array. • SUBSTITUTE(~,"W","ww") change "W" to "ww". • LEN(~)-1 counts the "w"; minus 1 for the leading "x". • MAX(~) return the largest one. # UiuaSBCS, 13 bytes ⬚0/↥⊜/+.◿3-@@  Try it! ⬚0/↥⊜/+.◿3-@@ -@@ # subtract @ character ◿3 # modulo three ⊜/+. # sum groups delimited by zero ⬚0/↥ # maximum using zero as default  # YASEPL, 86 bytes =s=1'=l®1=i=h=c1!¥i,1}7,"v",2=c2!}7,"w",3!c+3!}7,"W",4!c++4!c}4,h,5!h$c5!i+}2,l>h


and just for fun,

# ibe, 130 bytes

adddQmwwoadddWmwwpadddEmoiadadadadaddsRdfTmRakqdgUmRmYshUmQmwskIakwshUmWmeafImwakeshUmEmrafImeakrsgImOmtskOafOmIaktafYmwssYmTmqasO
`