| 1 | class Deque: |
| 2 | def __init__(self, src_arr=[], max_size=300000): |
| 3 | self.length = max(max_size, len(src_arr)) + 1 |
| 4 | self.buf = list(src_arr) + [None] * (self.length - len(src_arr)) |
| 5 | self.head = 0 |
| 6 | self.tail = len(src_arr) |
| 7 | |
| 8 | def __index(self, i): |
| 9 | l = len(self) |
| 10 | if not -l <= i < l: |
| 11 | raise IndexError("index out of range: " + str(i)) |
| 12 | if i < 0: |
| 13 | i += l |
| 14 | return (self.head + i) % self.length |
| 15 | |
| 16 | def __extend(self): |
| 17 | ex = self.length - 1 |
| 18 | self.buf[self.tail + 1 : self.tail + 1] = [None] * ex |
| 19 | self.length = len(self.buf) |
| 20 | if self.head > 0: |
| 21 | self.head += ex |
| 22 | |
| 23 | def is_full(self): |
| 24 | return len(self) >= self.length - 1 |
| 25 | |
| 26 | def is_empty(self): |
| 27 | return len(self) == 0 |
| 28 | |
| 29 | def append(self, x): |
| 30 | if self.is_full(): |
| 31 | self.__extend() |
| 32 | self.buf[self.tail] = x |
| 33 | self.tail += 1 |
| 34 | self.tail %= self.length |
| 35 | |
| 36 | def appendleft(self, x): |
| 37 | if self.is_full(): |
| 38 | self.__extend() |
| 39 | self.buf[(self.head - 1) % self.length] = x |
| 40 | self.head -= 1 |
| 41 | self.head %= self.length |
| 42 | |
| 43 | def pop(self): |
| 44 | if self.is_empty(): |
| 45 | raise IndexError() |
| 46 | ret = self.buf[(self.tail - 1) % self.length] |
| 47 | self.tail -= 1 |
| 48 | self.tail %= self.length |
| 49 | return ret |
| 50 | |
| 51 | def popleft(self): |
| 52 | if self.is_empty(): |
| 53 | raise IndexError() |
| 54 | ret = self.buf[self.head] |
| 55 | self.head += 1 |
| 56 | self.head %= self.length |
| 57 | return ret |
| 58 | |
| 59 | def __len__(self): |
| 60 | return (self.tail - self.head) % self.length |