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In PHP one type does almost everything: an array is an ordered hash map, serving as list, dictionary and stack at once. This path has you build the structures it stands in for, and the ones it cannot, in PHP, then sort, recurse and search graphs with them, and finish on graded interview problems. Free, in your browser, with a certificate on most courses.
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23 free certificates along the pathEach step is a set of existing Coddy courses, and every Start button opens them in PHP. The three courses not taught in PHP yet are listed after the steps.
array makes a good stack, why array_shift makes a poor queue, and what the hash map inside every array does for you.StartSplDoublyLinkedList is a structure you have written, SplMinHeap and SplMaxHeap are one idea facing two ways, and the balanced tree PHP does not ship is one you can build.Startsort() has been stable since PHP 8.0; after this step you know what that promise means and which of the eight sorts could keep it.Start$f = function ($n) use (&$f) { ... }, a detail worth knowing before an interview asks for a recursive closure. Dynamic programming and bit manipulation are listed after the steps, since they are taught in Python and C++.StartDedicated pageSplPriorityQueue is a max-heap, so Dijkstra either negates its distances or runs on a heap of your own from step two.Startarray doing every job.StartWrite real code, query databases, build websites, and master AI prompts. Our interactive lessons cover every skill modern developers need.
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Double or Nothing
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Promotion zoneRead, listen, test yourself, ask the AI, or look up anything you've already covered. Every lesson meets you where you are.
A variable is a named container that stores a value you can reference later in your program.
In Python, you create one by writing the name, an equals sign, then the value you want to store.
The value can change over time - reassigning the name simply points it to a new value.
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Certificate of CompletionPython Fundamentals
Add to LinkedInarray really is. PHP's array is an ordered hash map, which is why $a[] = $x and $a['key'] = $x both work, and why array_shift is slow: it renumbers every remaining element. Building a real stack, queue and hash table is how you learn which array operations are cheap and which quietly are not.in_array inside a loop is a linear search on every pass, where isset on a keyed array is constant time on average. The thinking that passes an interview is the thinking that fixes that page.&, |, ^, ~, << and >>.array for everything. PHP's array is flexible enough to be a list, a dictionary and a stack, which is exactly what hides the cost of each operation. Build the structures yourself and PHP is a perfectly good language to reason about algorithms in, and the natural one to interview in if PHP is your job.SplStack and SplQueue are a stack and a queue, both built on SplDoublyLinkedList; SplMinHeap and SplMaxHeap are heaps; SplPriorityQueue is a max-heap ordered by priority; and SplFixedArray is a fixed-size array with integer indexes that uses less memory than an array. The plain array is your hash table. There is no tree, trie or graph class, so those you write yourself, in steps one and two.array_shift slow for a queue in PHP?array_shift costs O(n) per dequeue, and quadratic time to empty. Use SplQueue, or keep a head index into the array and advance it instead. Step one has you build a queue yourself, which is the surest way to see the difference.sort() stable in PHP?sort(), usort(), asort() and the other sorting functions keep equal elements in their original order. Before 8.0 they made no such promise, so code that depended on the order of equal elements could behave differently between versions. Of the eight sorts in step three, merge sort and insertion sort are stable and quicksort and heap sort are not; after it, you know why.array keyed by the subproblem. One trap when porting bit tricks: if both operands of &, | or ^ are strings, PHP works on their characters' byte values and returns a string, so make sure the values are integers first.$next property. If those are new, Coddy's PHP course takes you there first, free, and this path picks up where it ends.