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Is using Random and OrderBy a good shuffle algorithm?
...t an O(n) shuffle. The code in the question "works" by basically giving a random (hopefully unique!) number to each element, then ordering the elements according to that number.
I prefer Durstenfield's variant of the Fisher-Yates shuffle which swaps elements.
Implementing a simple Shuffle extensio...
What are the disadvantages to declaring Scala case classes?
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First the good bits:
Everything immutable by default
Yes, and can even be overridden (using var) if you need it
Getters automatically defined
Possible in any class by prefixing params with val
Decent toString() implementation
Yes, very useful, but doable by hand on any class if nece...
If strings are immutable in .NET, then why does Substring take O(n) time?
... liked this question so much, I just blogged it. See Strings, immutability and persistence
The short answer is: O(n) is O(1) if n does not grow large. Most people extract tiny substrings from tiny strings, so how the complexity grows asymptotically is completely irrelevant.
The long answer is:
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Tools for analyzing performance of a Haskell program
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how to find out why this solution is so slow. Are there any commands that tell me where most of the computation-time is spend so I know which part of my haskell-program is slow?
Precisely! GHC provides many excellent tools, including:
runtime statistics
time profiling
heap profiling
t...
Modular multiplicative inverse function in Python
Does some standard Python module contain a function to compute modular multiplicative inverse of a number, i.e. a number y = invmod(x, p) such that x*y == 1 (mod p) ? Google doesn't seem to give any good hints on this.
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How to format strings using printf() to get equal length in the output?
...o functions, one which produces messages like Starting initialization... and another which checks return codes and outputs "Ok" , "Warning" or "Error" . However, the output that is produced is of the different length:
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Retaining file permissions with Git
...b content from our dev server to github, pull it to our production server, and spend the rest of the day at the pool.
8 A...
How to list the size of each file and directory and sort by descending size in Bash?
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Simply navigate to directory and run following command:
du -a --max-depth=1 | sort -n
OR add -h for human readable sizes and -r to print bigger directories/files first.
du -a -h --max-depth=1 | sort -hr
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How to read/write from/to file using Go?
...en trying to learn Go on my own, but I've been stumped on trying read from and write to ordinary files.
8 Answers
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Using sed, how do you print the first 'N' characters of a line?
...e first 100 characters:
cat file |colrm 101
It's been around for years and is in most linux's and bsd's (freebsd for sure), usually by default. I can't remember ever having to type apt-get install colrm.
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