d0ac45bcde
* Add Lua code for chapter 6 * Add Lua code for chapter 7 * Add Lua code for chapter 8 * Add Lua code for chapter 9
46 lines
867 B
Lua
46 lines
867 B
Lua
deque = {}
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function deque:new()
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self.__index = self
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return setmetatable({first = 0, last = -1}, self)
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end
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function deque:len()
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return self.last - self.first + 1
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end
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function deque:push_left(value)
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local first = self.first - 1
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self.first = first
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self[first] = value
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end
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function deque:push_right(value)
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local last = self.last + 1
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self.last = last
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self[last] = value
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end
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function deque:pop_left()
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local first = self.first
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if first > self.last then
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error "deque is empty"
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end
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local value = self[first]
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self[first] = nil
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self.first = first + 1
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return value
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end
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function deque:pop_right()
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local last = self.last
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if self.first > last then
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error "deque is empty"
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end
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local value = self[last]
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self[last] = nil
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self.last = last - 1
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return value
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end
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return deque |