Set and Hash_set

Original: http://blog.csdn.net/morewindows/article/details/7029587

The six set and Hash_set of STL series

Set and Hash_set are the more important containers in STL, and it is necessary to understand them deeply. In STL, set is a red black tree (Rb-tree) as the underlying data structure, Hash_set is a hash table (hash table) as the underlying data structure. Set can insert, delete, and find data in the case of a time complexity of O (Logn). The time complexity of the hash_set operation is more complex, depending on the hash function and the load situation of the hash table. The common functions of set and Hash_set are listed below:

For more functions of set and Hase_set, please refer to MSDN.

The use example of set is as follows (Hash_set):

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2. by Morewindows (http://blog.csdn.net/MoreWindows)
4. #include <set>
6. #include <ctime>
8. #include <cstdio>
10. Using namespace std;
14. int main ()
16. {
18. printf ("--set using by Morewindows (http://blog.csdn.net/MoreWindows)--\n\n");
20. const int maxn = 15;
22. int A[MAXN];
24. int i;
26. Srand (Time (NULL));
28. For (i = 0; i < MAXN; ++i)
30. A[i] = rand ()% (MAXN * 2);
34. set<int> Iset;
36. set<Int>::iterator pos;
40. //Inserting data Insert () There are three kinds of overloads
42. Iset.insert (A, A + MAXN);
46. ///The maximum number of data in the current collection
48. printf ("Number of current collections:%d Maximum capacity:%d\n", Iset.size (), iset.max_size ());
52. //output in sequence
54. printf ("Output all elements of the collection in turn-------\ n");
56. For (pos = Iset.begin (); pos! = Iset.end (); ++pos)
58. printf ("%d", *pos);
60. Putchar (' \ n ');
64. //Find
66. int findnum = MAXN;
68. printf ("Find out if%d exists-----------------------\ n", FindNum);
70. pos = Iset.find (FindNum);
72. if (pos! = Iset.end ())
74. printf ("%d exists \ n", FindNum);
76. Else
78. printf ("%d does not exist \ n", FindNum);
82. //Insert the data at the last position, and if the given location is incorrect, find the correct location and return to that location
84. pos = Iset.insert (--iset.end (), MAXN * 2);
86. printf ("already inserted%d\n", *pos);
90. //Delete
92. Iset.erase (MAXN);
94. printf ("deleted%d\n", MAXN);
98. //output in sequence
100. printf ("Output all elements of the collection in turn-------\ n");
102. For (pos = Iset.begin (); pos! = Iset.end (); ++pos)
104. printf ("%d", *pos);
106. Putchar (' \ n ');
108. return 0;
110. }

The results of the operation are as follows:

Set and Hash_set