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Is a Java hashmap search really O(1)?
I've seen some interesting claims on SO re Java hashmaps and their O(1) lookup time. Can someone explain why this is so? Unless these hashmaps are vastly different from any of the hashing algorithms I was bought up on, there must always exist a dataset that contains collisions.
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Quicksort vs heapsort
Both quicksort and heapsort do in-place sorting. Which is better? What are the applications and cases in which either is preferred?
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Permutations in JavaScript?
...s into an array prior to do any permutation, so you simply remove the join and split operation
var permArr = [],
usedChars = [];
function permute(input) {
var i, ch;
for (i = 0; i < input.length; i++) {
ch = input.splice(i, 1)[0];
usedChars.push(ch);
if (input.leng...
Heap vs Binary Search Tree (BST)
What is the difference between a heap and BST?
8 Answers
8
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How can I get a file's size in C? [duplicate]
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You need to seek to the end of the file and then ask for the position:
fseek(fp, 0L, SEEK_END);
sz = ftell(fp);
You can then seek back, e.g.:
fseek(fp, 0L, SEEK_SET);
or (if seeking to go to the beginning)
rewind(fp);
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Testing whether a value is odd or even
I decided to create simple isEven and isOdd function with a very simple algorithm:
22 Answers
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How to pad zeroes to a string?
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Strings:
>>> n = '4'
>>> print(n.zfill(3))
004
And for numbers:
>>> n = 4
>>> print(f'{n:03}') # Preferred method, python >= 3.6
004
>>> print('%03d' % n)
004
>>> print(format(n, '03')) # python >= 2.6
004
>>> print('{0:...
When splitting an empty string in Python, why does split() return an empty list while split('\n') re
I am using split('\n') to get lines in one string, and found that ''.split() returns an empty list, [] , while ''.split('\n') returns [''] . Is there any specific reason for such a difference?
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Using Linq to get the last N elements of a collection?
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This approach preserves item order without a dependency on any sorting, and has broad compatibility across several LINQ providers.
It is important to take care not to call Skip with a negative number. Some providers, such as the Entity Framework, will produce an ArgumentException when presented ...
What are the mathematical/computational principles behind this game?
...t (this is a bit different from Euclid).
Now, add "finite" into the soup and you have the question:
Can we have a geometry with just 2 points? With 3 points? With 4? With 7?
There are still open questions regarding this problem but we do know this:
If there are geometries with Q points, then Q...