Longest Run Tosses Matlab

Write an efficient function which computes the length of the longest run of heads in an arbitrary sequence of heads and tails ?

The excercise is about a coin toss and i would really appreciate if someone could help me with this excercise.

[James Tursa]

What have you done so far? What specific problems are you having with your code?

[Ameer Hamza]

BK, the purpose of answering questions on this forum is not just to solve a problem for the OP. It is about creating a knowledge-base for MATLAB related issues. Therefore, even if you found a different solution, the answers to this question are still useful for anyone else who stumbles upon a similar problem and come to this page. Therefore, I am pasting your original question as a comment. Otherwise, the answers lose their value.

[Ameer Hamza]

Berkay Kül Original Question

Title: Longest Run of heads in a sequence of coin tosses

Write an efficient function which computes the length of the longest run of heads in an arbitrary sequence of heads and tails ?

The excercise is about a coin toss and i would really appreciate if someone could help me with this excercise.

[Adam Danz]

@KBB's flag: I want to delete my question, because I found a code on my own which is working

KBB, in general, you should search for an answer before asking a question. Once you ask a question, volunteers may invest their time into answering it and at that point, you can't give them their time back. The return on thier investment is an answer that may benefit others in the future.

[madhan ravi]

KBB it's really clear that your professor found this link ;) and thank you for disrespecting others effort.

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[Walter Roberson]

at any one time you only need a few pieces of information:

• are you currently in a run
• length of the current run
• maximum length of run encountered so far

if you are not in a run and you encounter a T then move on to the next entry

if you are in a run and you encounter a T then compare the length of the current run to the maximum so far to determine if you have a new record. Afterwards either way mark yourself as no longer being in a run. then move on to the next entry.

if you are in a run and encounter a H then increment the length of the current run. Then move on to the next entry.

I left out a detail that you should be able to catch.

You can get away with using just two variables aside from the loop index.

Answer 2

[KSSV]

N = 2 ; % [1- heads, 2-tails]
toss = 100 ;  %number of tossings 
state = zeros(toss,1) ; 
for i = 1:toss
  state(i) = randperm(N,1) ;
end
% split the states which are continuous 1 and/or 2 
S = mat2cell(state, diff([0; find(diff(state)); size(state,1)]));
% Get the length of sequence of states 
L = cellfun(@length,S) ; 
% Get the maximum length sequence 
[val,id] = max(L) ;
fprintf("State:%d is repeated maximum of %d times\n",unique(S{id}),val)

[Walter Roberson]

this was clearly a homework assignment :(

[KSSV]

You should understand first how/ what the code is.

Thanks is accepting the answer. :)

Answer 3

[Stephen23]

Simpler and more efficient:

>> N = 17; % number of tosses
>> V = randi(2,1,N) % 1=tails 2=heads
V =
   2   1   2   2   2   2   2   2   1   1   2   2   1   1   1   2   2
>> D = diff([false,V==2,false]); % 2=heads
>> L = find(D<0)-find(D>0);
>> max(L)
ans =  6