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deque的數據結構示意圖:
技術要點:
隨機訪問每個元素,所需要的時間為常量。
在開頭和末尾增加元素所需時間與元素數目無關,在中間增加或刪除元素所需時間隨元素數目呈線性變化。
可動態增加或減少元素,內存管理自動完成,不提供用于內存管理的成員函數。參考代碼:
1 /************************************************************************
2 * deque:
3 * 1, 分塊分配空間,非順序存儲,隨機訪問是通過復雜的iterator實現
4 * 2, 在前后插入數據時間復雜度為O(1)
5 * 3, 迭代器失效:
6 * If an element is inserted into an empty sequence, or if an element is
7 erased to leave an empty sequence, then iterators earlier returned
8 by begin and end become invalid.
9
10 If an element is inserted at the first position of the deque,
11 then all iterators, but no references, that designate existing
12 elements become invalid.
13
14 If an element is inserted at the end of the deque, then end and all
15 iterators, but no references, that designate existing elements become invalid.
16
17 If an element is erased at the front of the deque, only that iterator
18 and references to the erased element become invalid.
19
20 If the last element is erased from the end of the deque, only that
21 iterator to the final element and references to the erased element become invalid.
22
23 Otherwise, inserting or erasing an element invalidates all iterators and references.
24
25 * by Kusamba@126.com http://www.shnenglu.com/kusamba
26 */
27 void deque_test()
28 {
29 deque<int> dqInt;
30
31 int nSize = dqInt.size();
32 int nMaxSiz = dqInt.max_size();
33
34 dqInt.resize(100);
35 dqInt.resize(10, 2);
36
37 /**
38 * push_back
39 */
40 for (int i = 0; i < 10; ++i)
41 {
42 dqInt[i] = i + 1;
43 }
44 for (int i = 0; i < 10; ++i)
45 {
46 dqInt.push_back(i + 11);
47 }
48
49 /**
50 * insert
51 */
52 for (deque<int>::iterator it = dqInt.begin(); it != dqInt.end();)
53 {
54 if (*it % 3 == 0) //在3的倍數的元素后面插入100
55 {
56 it = dqInt.insert(it + 1, 100);
57 }
58 else
59 {
60 ++it;
61 }
62 }
63
64 /**
65 * erase
66 */
67 for (deque<int>::iterator it = dqInt.begin(); it != dqInt.end();)
68 {
69 if (*it == 4)
70 {
71 it = dqInt.erase(it);
72 }
73 else
74 {
75 ++it;
76 }
77 }
78
79 /**
80 * traverse
81 */
82 printf("print deque: ");
83 for (int i = 0; i < dqInt.size(); ++i)
84 {
85 printf("%d ", dqInt[i]);
86 }
87 printf("\n");
88
89 /**
90 * pop
91 */
92 while (!dqInt.empty())
93 {
94 int nItemVal = dqInt.front();
95 dqInt.pop_front();
96 }
97 }