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Binary Heap
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| function BinaryHeap(cmp) | |
| local heap = {} | |
| local function push(el) | |
| table.insert(heap, el) | |
| local i = #heap | |
| while i > 1 do | |
| local parent = math.floor(i / 2) | |
| if cmp(heap[parent], heap[i]) then | |
| break | |
| end | |
| heap[i], heap[parent], i = heap[parent], heap[i], parent | |
| end | |
| end | |
| local function pop() | |
| if #heap == 0 then | |
| return | |
| end | |
| local size = #heap | |
| local top = heap[1] | |
| heap[1], heap[size] = heap[size], heap[1] | |
| table.remove(heap, size) | |
| local i = 1 | |
| while i < size-1 do | |
| local left = i * 2 | |
| local right = i * 2 + 1 | |
| local child | |
| if right <= size and cmp(heap[right], heap[left]) then | |
| child = right | |
| elseif left <= size then | |
| child = left | |
| else | |
| break | |
| end | |
| if cmp(heap[i], heap[child]) then | |
| break | |
| end | |
| heap[i], heap[child], i = heap[child], heap[i], child | |
| end | |
| return top | |
| end | |
| return { | |
| size = function () return #heap end, | |
| push = push, | |
| pop = pop | |
| } | |
| end |
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