notation

问题 Does anyone know of any good resources to learn big o notation? In particular learning how to walk through some code and being able to see that it would be O(N^2) or O(logN)? Preferably something that can tell me why a code like this is equal to O(N log N) def complex(numbers): N = len(numbers) result = 0 for i in range(N): j = 1 while j < N: result += numbers[i]*numbers[j] j = j*2 return result Thanks! 回答1: To start, let me define to you what O(N log N) is. It means, that the program will

问题 The following works as expected: $values = @( ("a", "b"), ("c", "d") ) foreach($value in $values) { write-host "Value 0 =" $value[0] write-host "Value 1 =" $value[1] } which results(1) in: Value 0 = a Value 1 = b Value 0 = c Value 1 = d But if I change the $values variable to: $values = @( ("a", "b") ) the result(2) is: Value 0 = a Value 1 = Value 0 = b Value 1 = whereas I would have expected the result(3) to be: Value 0 = a Value 1 = b Changing the $value to: $values = @( ("a"), ("b") )

问题 The following works as expected: $values = @( ("a", "b"), ("c", "d") ) foreach($value in $values) { write-host "Value 0 =" $value[0] write-host "Value 1 =" $value[1] } which results(1) in: Value 0 = a Value 1 = b Value 0 = c Value 1 = d But if I change the $values variable to: $values = @( ("a", "b") ) the result(2) is: Value 0 = a Value 1 = Value 0 = b Value 1 = whereas I would have expected the result(3) to be: Value 0 = a Value 1 = b Changing the $value to: $values = @( ("a"), ("b") )

问题 The following works as expected: $values = @( ("a", "b"), ("c", "d") ) foreach($value in $values) { write-host "Value 0 =" $value[0] write-host "Value 1 =" $value[1] } which results(1) in: Value 0 = a Value 1 = b Value 0 = c Value 1 = d But if I change the $values variable to: $values = @( ("a", "b") ) the result(2) is: Value 0 = a Value 1 = Value 0 = b Value 1 = whereas I would have expected the result(3) to be: Value 0 = a Value 1 = b Changing the $value to: $values = @( ("a"), ("b") )

问题 The following works as expected: $values = @( ("a", "b"), ("c", "d") ) foreach($value in $values) { write-host "Value 0 =" $value[0] write-host "Value 1 =" $value[1] } which results(1) in: Value 0 = a Value 1 = b Value 0 = c Value 1 = d But if I change the $values variable to: $values = @( ("a", "b") ) the result(2) is: Value 0 = a Value 1 = Value 0 = b Value 1 = whereas I would have expected the result(3) to be: Value 0 = a Value 1 = b Changing the $value to: $values = @( ("a"), ("b") )

问题 I am sorry if this doesn't really belong here but I'm looking for a way to describe the mathematical background of my code. Using numpy I sum two more dimensional arrays: a.shape = (10, 5, 2) b.shape = (5, 2) c = a + b c.shape = (10, 5, 2) Is there a pure mathematical notation for this (so WITHOUT indroducing for-loops or numpy conventions in my text)? What I'm trying to avoid is to have to write something like this: c_{1, y, z} = a_{1, y, z} + b_{y, z} c_{2, y, z} = a_{2, y, z} + b_{y, z} ..

问题 I am sorry if this doesn't really belong here but I'm looking for a way to describe the mathematical background of my code. Using numpy I sum two more dimensional arrays: a.shape = (10, 5, 2) b.shape = (5, 2) c = a + b c.shape = (10, 5, 2) Is there a pure mathematical notation for this (so WITHOUT indroducing for-loops or numpy conventions in my text)? What I'm trying to avoid is to have to write something like this: c_{1, y, z} = a_{1, y, z} + b_{y, z} c_{2, y, z} = a_{2, y, z} + b_{y, z} ..

问题 I am using JSON within my javascript and I am trying to get a string value for the dot notation representation. For example AAA.BBB[0].CCC.DDD[5].EEE = 123 in JSON dot notation format. But I want to get the value AAA.BBB[0].CCC.DDD[5].EEE as a String so I can save it for later use to allow me to modify my JSON code directly. Is there a method in Javascript or jQuery that can return a string value representation? *EDIT I am converting JSON data into a list structure, and I want to save the AAA

问题 I see an unfamiliar notation in the Android source code: *= For example: density *= invertedRatio; I am not familiar with the star-equals notation. Can somebody explain it? 回答1: density *= invertedRatio; is a shortened version of density = density * invertedRatio; This notation comes from C. 回答2: In Java, the *= is called a multiplication compound assignment operator. It's a shortcut for density = density * invertedRatio; Same abbreviations are possible e.g. for: String x = "hello "; x +=

问题 I'm trying to declare a NamedQuery on a mapped superclass, but I obtain this error: org.hibernate.hql.ast.QuerySyntaxException: VoipCall is not mapped [select v from VoipCall v where v.audioFile = :audioFile] We use hibernate, but we prefer to use JPA standard notation. Here is the code: @MappedSuperclass @NamedQueries(value = { @NamedQuery(name = "getVoipCallsForAudio", query = "select v from VoipCall v where v.audioFile = :audioFile") }) public abstract class VoipCall implements