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Why does this method print 4?

... I think the others have done a good job at explaining why cnt > 0, but there's not enough details regarding why cnt = 4, and why cnt varies so widely among different settings. I will attempt to fill that void here. Let X be the total stack size M be the stack sp...
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What are the differences between NP, NP-Complete and NP-Hard?

...lem: A problem with a yes or no answer. Now, let us define those complexity classes. P P is a complexity class that represents the set of all decision problems that can be solved in polynomial time. That is, given an instance of the problem, the answer yes or no can be decided in polynomial t...
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join list of lists in python [duplicate]

Is the a short syntax for joining a list of lists into a single list( or iterator) in python? 15 Answers ...
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What's the @ in front of a string in C#?

...ored. So "C:\\Users\\Rich" is the same as @"C:\Users\Rich" There is one exception: an escape sequence is needed for the double quote. To escape a double quote, you need to put two double quotes in a row. For instance, @"""" evaluates to ". ...
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Ruby's ||= (or equals) in JavaScript?

I love Ruby's ||= mechanism. If a variable doesn't exist or is nil , then create it and set it equal to something: 6 Ans...
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What does 'predicate' mean in the context of computer science? [duplicate]

Specifically I've seen it used in the context of text filtering. As if "predicate" == "filter criteria". 7 Answers ...
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Adding an arbitrary line to a matplotlib plot in ipython notebook

...rough the ipython notebook. I'm trying to add some annotation lines to an existing graph and I can't figure out how to render the lines on a graph. So, for example, if I plot the following: ...
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Determine the number of NA values in a column

... Thank you for this. To expand this a little bit. In counting amount of arbitrary value, other than NA is writing a boolean function is.value and then using sum(is.value(df$col)) the way to go or is there a more concise direct syntax for this? ...
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Test if executable exists in Python?

In Python, is there a portable and simple way to test if an executable program exists? 21 Answers ...
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Why can't C++ be parsed with a LR(1) parser?

...n of C++ parsing, which states that: "C++ grammar is ambiguous, context-dependent and potentially requires infinite lookahead to resolve some ambiguities". It goes on to give a number of examples (see page 147 of the pdf). The example is: int(x), y, *const z; meaning int x; int y; i...