length of the largest sub sequence sorted in a non-decreasing order.

For an assignment, I have done question 3a, but i don't know how would do/ approach question 3b. Any help would be appriciated. :)

The questions was:

Generate a sequence of 1000 random integers between 1 and 100.

(a) Using a loop, count the number of times three consecutive numbers are sorted in a non-descending order. Display the count in the command window.

(b)* Using nested loops, find the length of the largest subsequence sorted in a non-decreasing order. Display the result in the command window.

I have provided the code i have done for question 3a

h=randi(100,1,1000)
count =0
for i =1:998
    if h(i)<=h(i+1) && h(i+1) <= h(i+2)
        count = count+1
    end
end

Answer 1

[Image Analyst]

Inside the "if", you know you have a sequence of at least 3 in a row. If there are 20 numbers in that sequence, you're going to have more than 1 count for that sequence. Not sure what is wanted. For example, is [3,4,5,6] one sequence or two? If it's one, then you might have to switch to a while loop.

Anyway, inside the "if" you need to have a while, something like

k2 = i;
if h2 < length(h);
    while h(k2+1) > h(k2) 
         % etc incrementing the length of this particular sequence.
         

[Oscar Tsang]

Sorry, didn't know the image wasn't clear enough. I have written the question out. I have done question a but not question b becasue i don't know how to modify question a to get question b.

[Image Analyst]

OK, but my answer remains the same. Once you are "in" a sequence, you need to use a while loop to find the end of it.

[Oscar Tsang]

Thank-you so much!!!!!

[Oscar Tsang]

is this it, becasue its a endless loop.

h=randi(100,1,1000)
count=0;
for i =1:998
    if h(i)<=h(i+1) && h(i+1) <= h(i+2)
         
while h(k2+1) > h(k2) 
        count = count+1
end
    end
end