Körperbewegung

mods/modlib/heap.lua

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+-- Localize globals
+local math_floor, setmetatable, table_insert = math.floor, setmetatable, table.insert
+
+-- Set environment
+local _ENV = {}
+setfenv(1, _ENV)
+
+local metatable = {__index = _ENV}
+
+function less_than(a, b) return a < b end
+
+--> empty min heap
+function new(less_than)
+	return setmetatable({less_than = less_than}, metatable)
+end
+
+function push(self, value)
+	table_insert(self, value)
+	local function heapify(index)
+		if index == 1 then
+			return
+		end
+		local parent = math_floor(index / 2)
+		if self.less_than(self[index], self[parent]) then
+			self[parent], self[index] = self[index], self[parent]
+			heapify(parent)
+		end
+	end
+	heapify(#self)
+end
+
+function pop(self)
+	local value = self[1]
+	local last = #self
+	if last == 1 then
+		self[1] = nil
+		return value
+	end
+	self[1], self[last] = self[last], nil
+	last = last - 1
+	local function heapify(index)
+		local left_child = index * 2
+		if left_child > last then
+			return
+		end
+		local smallest_child = left_child + 1
+		if smallest_child > last or self.less_than(self[left_child], self[smallest_child]) then
+			smallest_child = left_child
+		end
+		if self.less_than(self[smallest_child], self[index]) then
+			self[index], self[smallest_child] = self[smallest_child], self[index]
+			heapify(smallest_child)
+		end
+	end
+	heapify(1)
+	return value
+end
+
+-- Export environment
+return _ENV