Common usage of C + + set

Set Collection container: realizes the red black tree's balanced binary search tree data structure, when inserting the element, it automatically adjusts the binary tree arrangement, puts the element in the appropriate position, guarantees each sub-tree root node key value is bigger than the left subtree all node's key value, is less than the right subtree all node's key value; In addition, Also ensure that the height of the left subtree of the root node is equal to the height of the right sub-tree.

The balanced binary search tree uses the middle sequence traversal algorithm, the retrieval efficiency is higher than the vector, the deque and the list and so on, in addition uses the middle sequence traversal can the key value to traverse from small to large.
The main purpose of constructing set sets is to retrieve quickly and not to modify key values directly.

Common operations:
1. Element insert: Insert ()
2. Middle sequence traversal: vector-like traversal (with iterators)
3. Reverse traversal: Use the reverse iterator reverse_iterator.
Cases:
Set<int> s;
......
Set<int>::reverse_iterator RIT;
For (Rit=s.rbegin (); Rit!=s.rend (); rit++)
4. Element removal: As with insertions, it can be efficiently removed and automatically adjusted to make the red-black tree balanced.
Set<int> s;
S.erase (2); Delete an element with a key value of 2
S.clear ();
5. Element search: Find (), if found, returns the position of the key-value iterator, otherwise, returns a position after the last element.
Set<int> s;
Set<int>::iterator it;
It=s.find (5); Find an element with a key value of 5
if (It!=s.end ())//Found
cout<<*it<<endl;
else//not found
cout<< "not Found";
6. Custom comparison functions
(1) The element is not a struct:
Cases:
Custom comparison function MyComp, overloaded "()" operator
struct MYCOMP
{
BOOL Operator () (const your_type &a,const your_type &b)
[
Return a.data-b.data>0;
}
}
set<int,mycomp>s;
......
Set<int,mycomp>::iterator it;
(2) If the element is a struct, the comparison function can be written directly in the structure body.
Cases:
struct INFO
{
String name;
Float score;
Overloaded "<" operator, custom collation
BOOL operator < (const Info &a) const
{
Press score to arrange from large to small
Return a.score<score;
}
}
Set<info> s;
......
Set<info>::iterator it;

Transferred from: http://blog.csdn.net/wangran51/article/details/8836160

Common usage of C + + set