#Binary-Heaps# Implementation of binary heaps data structure in pure Lua

##Usage## Add 'binary_heap.lua' file inside your project. Call it using require function. It will return a table containing a set of functions, acting as a class.

##API##

• heap:new() : Returns a new heap ( a Min-Heap by default).
• heap() : Same as heap:new()
• heap:empty() : Checks if a heap is empty.
• heap:getSize() : Returns the size of the heap.
• heap:clear() : Clears a heap
• heap:leftChildIndex(index) : Returns the left child index of element at position index in the heap
• heap:rightChildIndex(index) : Returns the right child index of element at position index in the heap
• heap:parentIndex(index) : Returns the parent index of element at position index in the heap
• heap:insert(value,linkedData) : Inserts value with linked data in the heap and percolates it up at its proper place.
• heap:add(value, linkedData) : Alias to heap.insert
• heap:replace(value,linkedData) : Saves the top of the heap, adds a new element at the top and reorders the heap.
• heap:pop() : Pops the top element, reorders the heap and returns this element unpacked : value first then data linked
• heap:checkIndex() : checks existence of an element at position index in the heap.
• heap:reset(function) : Reorders the current heap regards to the new comparison function given as argument
• heap:merge(other) : merge the current heap with another
• heap:isValid() : Checks if a heap is valid
• heap:heap(item) : Restores the heap property (in case the heap was earlier found non-valid)

##Additionnal features##

h1+h2 : Returns a new heap with all data stored inside h1 and h2 heaps
tostring(h) : Returns a string representation of heap h
print(h) : Prints current heap h as a string

By default, you create Min-heaps. If you do need Max-heaps, you can easily create them this way:

local comp = function(a,b) return a>b end
local myHeap = heap(comp)

##Chaining## Some functions can be chained together, as they return the heap itself:

heap:clear()
heap:add() or heap:insert()
heap:reset()	
heap:merge()
heap:heap()

Example:

h = Heap()
h:add(1):add(2):heap():clear():add(3):add(4):merge(Heap()):reset()
print(h)

#Documentation used#

• Algolist.net data structure course
• Victor S.Adamchik's Lecture on Cs.cmu.edu
• RPerrot's Article on Developpez.com

##License## This work is under MIT-LICENSE Copyright (c) 2012 Roland Yonaba

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