|
| 1 | +""" |
| 2 | +https://en.wikipedia.org/wiki/Queue_(abstract_data_type) |
| 3 | +""" |
| 4 | +from typing import Any |
| 5 | + |
| 6 | + |
| 7 | +class Queue: |
| 8 | + def __init__(self) -> None: |
| 9 | + self.queue = [] |
| 10 | + |
| 11 | + def __len__(self) -> int: |
| 12 | + """ |
| 13 | + >>> queue = Queue() |
| 14 | + >>> len(queue) |
| 15 | + 0 |
| 16 | + >>> for i in range(0, 5): |
| 17 | + ... assert len(queue) == i |
| 18 | + ... queue.enqueue(i) |
| 19 | + >>> len(queue) |
| 20 | + 5 |
| 21 | + """ |
| 22 | + return len(self.queue) |
| 23 | + |
| 24 | + def __str__(self) -> str: |
| 25 | + """ |
| 26 | + >>> queue = Queue() |
| 27 | + >>> str(queue) |
| 28 | + '' |
| 29 | + >>> for i in range(1, 6): |
| 30 | + ... queue.enqueue(i) |
| 31 | + >>> str(queue) |
| 32 | + '1 <- 2 <- 3 <- 4 <- 5' |
| 33 | + """ |
| 34 | + return " <- ".join([str(item) for item in self.queue]) |
| 35 | + |
| 36 | + def size(self) -> int: |
| 37 | + """ |
| 38 | + >>> queue = Queue() |
| 39 | + >>> queue.size() |
| 40 | + 0 |
| 41 | + >>> for i in range(0, 5): |
| 42 | + ... assert queue.size() == i |
| 43 | + ... queue.enqueue(i) |
| 44 | + >>> queue.size() |
| 45 | + 5 |
| 46 | + """ |
| 47 | + return len(self) |
| 48 | + |
| 49 | + def is_empty(self) -> bool: |
| 50 | + """ |
| 51 | + >>> queue = Queue() |
| 52 | + >>> queue.is_empty() |
| 53 | + True |
| 54 | + >>> queue.enqueue('a') |
| 55 | + >>> queue.enqueue('b') |
| 56 | + >>> queue.is_empty() |
| 57 | + False |
| 58 | + """ |
| 59 | + return len(self) == 0 |
| 60 | + |
| 61 | + def enqueue(self, item: Any) -> None: |
| 62 | + """ |
| 63 | + >>> queue = Queue() |
| 64 | + >>> str(queue) |
| 65 | + '' |
| 66 | + >>> for i in range(0, 5): |
| 67 | + ... queue.enqueue(i) |
| 68 | + >>> str(queue) |
| 69 | + '0 <- 1 <- 2 <- 3 <- 4' |
| 70 | + """ |
| 71 | + self.queue.append(item) |
| 72 | + |
| 73 | + def dequeue(self) -> Any: |
| 74 | + """ |
| 75 | + >>> queue = Queue() |
| 76 | + >>> for i in range(0, 5): |
| 77 | + ... queue.enqueue(i) |
| 78 | + >>> str(queue) |
| 79 | + '0 <- 1 <- 2 <- 3 <- 4' |
| 80 | + >>> queue.dequeue() |
| 81 | + 0 |
| 82 | + >>> queue.dequeue() |
| 83 | + 1 |
| 84 | + >>> str(queue) |
| 85 | + '2 <- 3 <- 4' |
| 86 | + >>> for i in range(2, 5): |
| 87 | + ... assert queue.dequeue() == i |
| 88 | + >>> str(queue) |
| 89 | + '' |
| 90 | + """ |
| 91 | + if self.is_empty(): |
| 92 | + raise IndexError("dequeue from empty queue") |
| 93 | + ret_item = self.queue[0] |
| 94 | + self.queue = self.queue[1:] |
| 95 | + return ret_item |
| 96 | + |
| 97 | + def peek(self) -> Any: |
| 98 | + """ |
| 99 | + >>> queue = Queue() |
| 100 | + >>> queue.enqueue("Python") |
| 101 | + >>> queue.enqueue("Java") |
| 102 | + >>> queue.enqueue("C") |
| 103 | + >>> queue.peek() |
| 104 | + 'Python' |
| 105 | + >>> queue.dequeue() |
| 106 | + 'Python' |
| 107 | + >>> queue.dequeue() |
| 108 | + 'Java' |
| 109 | + """ |
| 110 | + if self.is_empty(): |
| 111 | + raise IndexError("dequeue from empty queue") |
| 112 | + return self.queue[0] |
| 113 | + |
| 114 | + def clear(self) -> None: |
| 115 | + """ |
| 116 | + >>> queue = Queue() |
| 117 | + >>> for i in range(1, 6): |
| 118 | + ... queue.enqueue(i) |
| 119 | + >>> str(queue) |
| 120 | + '1 <- 2 <- 3 <- 4 <- 5' |
| 121 | + >>> queue.clear() |
| 122 | + >>> str(queue) |
| 123 | + '' |
| 124 | + """ |
| 125 | + self.queue = [] |
| 126 | + |
| 127 | + |
| 128 | +if __name__ == "__main__": |
| 129 | + from doctest import testmod |
| 130 | + |
| 131 | + testmod() |
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