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大道 石井


Last seen: 6 days ago Active since 2021

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  • ASEE Challenge Master
  • Cody Challenge Master
  • Indexing II Master
  • Indexing I Master
  • CUP Challenge Master
  • Project Euler I
  • Matrix Patterns II Master
  • Community Group Solver
  • Introduction to MATLAB Master
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Longest Collatz Sequence
Inspired by Projet Euler n°14. The Collatz iterative sequence (See Cody problem n° 2103 and 211) is defined for the set of po...

16 days ago

Solved


Sum of big primes without primes
Inspired by Project Euler n°10 (I am quite obviously a fan). With problem n°250 by Doug, you can find some global methods to ...

16 days ago

Solved


How to subtract?
*&plusmn &plusmn &plusmn &plusmn &plusmn &plusmn &plusmn &plusmn &plusmn &plusmn &plusmn* * Imagine you need to subtract one...

19 days ago

Solved


MATLAB Counter
Write a function f = counter(x0,b) to construct a counter handle f that counts with an initial value x0 and a step size b. E...

19 days ago

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Missing five
Convert decimal numbers to a base-9 notation missing the digit *5* <<http://www.alfnie.com/software/missing5.jpg>> Too man...

20 days ago

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Octoberfest festival
A group of students decided to visit Octoberfest festival. First they ordered one beer, then after half-hour they taken one more...

20 days ago

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Circle/Pentagon Overlap
Your function will be provided with the five vertices of a pentagon (p) as well as the center point (cp) and radius (r) of a cir...

20 days ago

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Inscribed Pentagon?
Your function will be provided with the five vertices of a pentagon (p) as well as the center point (cp) and radius (r) of a cir...

20 days ago

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Pentagonal Numbers
Your function will receive a lower and upper bound. It should return all pentagonal numbers within that inclusive range in ascen...

20 days ago

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Energy of a photon
*&#9883 &#9762 &#9883 &#9762 &#9883 &#9762 &#9883* Given the frequency F of a photon in giga hertz. Find energy E of this...

21 days ago

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Solitaire Cipher
Implement the <http://en.wikipedia.org/wiki/Solitaire_(cipher) solitaire cipher>. Since this is from Wikipedia, I am capturin...

21 days ago

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Renaming a field in a structure array
MATLAB has a <http://www.mathworks.com/help/techdoc/ref/setfield.html setfield> and a <http://www.mathworks.com/help/techdoc/ref...

21 days ago

Solved


Calculate the Levenshtein distance between two strings
This problem description is lifted from <http://en.wikipedia.org/wiki/Levenshtein_distance>. The Levenshtein distance betwee...

21 days ago

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Scrabble Scores
Given a word, determine its score in <http://en.wikipedia.org/wiki/Scrabble Scrabble>. The input string will always be provi...

21 days ago

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Given two arrays, find the maximum overlap
Given two arrays s1 and s2, create a new array s3 which is as short as possible and contains both arrays. If s1 = [1 2 3 4 5]...

21 days ago

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Set a diagonal
Given a matrix M, row vector v of appropriate length, and diagonal index d (where 0 indicates the main diagonal and off-diagonal...

22 days ago

Solved


Decimation - Optimized for speed
This problem is similar to http://www.mathworks.com/matlabcentral/cody/problems/1092-decimation, only this time the score will b...

22 days ago

Solved


Decimation
When dealing to the Roman Army, the term decimate meant that the entire unit would be broken up into groups of ten soldiers, and...

22 days ago

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Create logical matrix with a specific row and column sums
Given two numbers *|n|* and *|s|*, build an |n-by-n| logical matrix (of only zeros and ones), such that both the row sums and th...

22 days ago

Solved


Put two time series onto the same time basis
Use interpolation to align two time series onto the same time vector. This is a problem that comes up in <http://www.mathwork...

22 days ago

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Joining Ranges
You are given a n-by-2 matrix. Each row represents a numeric range, e.g. x = [0 5; 10 3; 20 15; 16 19; 25 25] contains...

22 days ago

Solved


Return a list sorted by number of consecutive occurrences
Inspired by Problem 38 by Cody Team. Given a vector x, return a vector y of the values in x sorted by the number of CONSECUTIVE...

22 days ago

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Construct an index vector from two input vectors in vectorized fashion
Create an index vector defined by two input vectors, one defining the beginnings of one or more index ranges, and the other defi...

22 days ago

Solved


Specific Element Count
Given a vector _v_ and a element _e_, return the number of occurrences of _e_ in _v_. Note: NaNs are equal and there may be n...

23 days ago

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Find the largest value in the 3D matrix
Given a 3D matrix A, find the largest value. Example >> A = 1:9; >> A = reshape(A,[3 1 3]); >> islargest(A) a...

23 days ago

Solved


Return unique values without sorting
If the input vector A is [42 1 1], the output value B must be the unique values [42 1] The *values of B are in the s...

23 days ago

Solved


"Low : High - Low : High - Turn around " -- Create a subindices vector
Let two vectors *lo* and *hi* be given. The job is to create a index vector like so idx = [lo(1):hi(1) lo(2):hi(2) ...]...

23 days ago

Solved


Return elements unique to either input
Given two numeric inputs a and b, return a row vector that contains the numbers found in only a or only b, but not both. For ex...

23 days ago

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middleAsColumn: Return all but first and last element as a column vector
Given input A, return all but the first and last elements, arranged as a column vector. (I.e., all dimensions after the first s...

23 days ago

Solved


Matrix indexing with two vectors of indices
Given a matrix M and two index vectors a and b, return a row vector x where x(i) = M(a(i),b(i)).

23 days ago

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