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

Question

Oscar Tsang 2019-3-3

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/447957-length-of-the-largest-sub-sequence-sorted-in-a-non-decreasing-order

评论： Oscar Tsang 2019-3-3

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

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Image Analyst 2019-3-3

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/447957-length-of-the-largest-sub-sequence-sorted-in-a-non-decreasing-order#answer_363563

在 MATLAB Online 中打开

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.
         

4 个评论
显示 2更早的评论隐藏 2更早的评论

Oscar Tsang 2019-3-3

Thank-you so much!!!!!

Oscar Tsang 2019-3-3

在 MATLAB Online 中打开

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