刘庆伟

Last seen: 3 days ago | Active since 2025

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Finding peaks
Find the peak values in the signal. The peak value is defined as the local maxima. For example, x= [1 12 3 2 7 0 3 1 19 7]; ...

6 days ago

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Max index of 3D array
Given a three dimensional array M(m,n,p) write a code that finds the three coordinates x,y,z of the Maximum value. Example ...

6 days ago

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Insert zeros into vector
Insert zeros after each elements in the vector. Number of zeros is specified as the input parameter. For example: x = [1 ...

6 days ago

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Change the sign of even index entries of the reversed vector
change the signs of the even index entries of the reversed vector example 1 vec = [4 -1 -2 9] ans = [9 2 -1 -4] example2...

6 days ago

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Implement a bubble sort technique and output the number of swaps required
A bubble sort technique compares adjacent items and swaps them if they are in the wrong order. This is done recursively until al...

6 days ago

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Create an n-by-n null matrix and fill with ones certain positions
The positions will be indicated by a z-by-2 matrix. Each row in this z-by-2 matrix will have the row and column in which a 1 has...

6 days ago

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Unique values without using UNIQUE function
You must return unique values in a vector in *stable* mode without using the unique function. About stable order flag: ...

6 days ago

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Find nth maximum
Find nth maximum in a vector of integer numbers. Return NaN if no such number exists. x = [2 6 4 9 -10 3 1 5 -10]; So ...

7 days ago

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Create an index-powered vector
Given a input vector x, return y as index-powered vector as shown below. Example x = [2 3 6 9] then y should be [...

7 days ago

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Find last zero for each column
Given a numeric array of arbitrary size, return the row index of the last zero for each column. If a column contains all nonzero...

7 days ago

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Calculate the Number of Sign Changes in a Row Vector (No Element Is Zero)
For a row vector: V=[7 1 2 -3] there is one sign change (from 2 to -3). So, the function you write must return N=1. F...

7 days ago

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Symmetry of vector
Determine whether the vector is symmetric or not (vector could be even or odd in length). For example: x = [1 2 3 3 2 1] is s...

7 days ago

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Alternating sum
Given vector x, calculate the alternating sum y = x(1) - x(2) + x(3) - x(4) + ...

7 days ago

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Golomb's self-describing sequence (based on Euler 341)
The Golomb's self-describing sequence {G(n)} is the only nondecreasing sequence of natural numbers such that n appears exactly G...

7 days ago

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Square Digits Number Chain Terminal Value (Inspired by Project Euler Problem 92)
Given a number _n_, return the terminal value of the number chain formed by summing the square of the digits. According to the P...

7 days ago

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"Look and say" sequence
What's the next number in this sequence? * [0] * [1 0] * [1 1 1 0] * [3 1 1 0] * [1 3 2 1 1 0] This a variant on the w...

7 days ago

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Project Euler: Problem 6, Natural numbers, squares and sums.
The sum of the squares of the first ten natural numbers is, 1^2 + 2^2 + ... + 10^2 = 385 The square of the sum of the first ...

7 days ago

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Sum of first n terms of a harmonic progression
Given inputs a, d and n, return the sum of the first n terms of the harmonic progression a, a/(1+d), a/(1+2d), a/(1+3d),....

7 days ago

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How many days?!?
Christmas is coming earlier and earlier each year. Thanks to rampant commercialism and Christmas Creep, "The Twelve Days of Chr...

7 days ago

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Radiation Heat Transfer — View Factors (1)
View factors (aka configuration factors) are utilized in some radiation heat transfer models to estimate heat transfer rates bet...

7 days ago

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Calculate the Distance to Source of Lightning
Lightning discharge heats air rapidly with lightning channels reaching temperatures of up to 50,000 degrees Fahrenheit (which is...

7 days ago

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Where the Four Corners Am I?
The "Four Corners" region of the US is where Colorado, Utah, Arizona, and New Mexico all meet - the only place where four states...

7 days ago

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Minkowski distance

7 days ago

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The cake is a lie...
You're hosting a birthday party with a large number of screaming children. Fortunately, you have a gigantic sheet cake in front...

7 days ago

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Fractal: area and perimeter of Koch snowflake
Starting from an equilateral triangle with side 's', what is the area and perimeter of Koch snowflake at n'th recursive iteratio...

7 days ago

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Similar Triangles - find the height of the tree
Given the height, h1, of a power pole, shorter than a tree, a given distance, x2 away, please find h2, height of the tree. Pleas...

7 days ago

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Air Mass to Star for an Observer at Mean Sea Level
Air mass is a measure of how much atmosphere light from a source above the atmosphere (eg sun, planet, star) has to travel throu...

7 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...

7 days ago

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Snow Accumulation and Structural Risks To Residential Properties
The density of snow depends on the amount of liquid water it contains: Dry Snow is about 50 kg/m^3 Wet Snow is about 200 kg/m^...

7 days ago

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How many Christmas presents under the tree?
For many families at Christmas, each family member gives 1 present to every other family member. The main exception is that chil...

7 days ago