Copyright @ Joel Jiang（江東敏） at 2017.07.21 13:00 p.m
in Shenzhen.China. LIST- TE- E11 -01
1.Deque
Deque(usually pronounced like"deck") is an irregular acronym ofdouble-endedqueue. Double-ended queues are sequence containers with dynamic sizes that can be expanded or contracted on both ends (either its front or its back).
"In computer science, a queue is a particular kind of abstract data type or collection in which the entities in the collection are kept in order and the principal (or only) operations on the collection are the addition of entities to the rear terminal position, known as en queue,and removal of entities from the front terminal position, known as dequeue. This makes the queue a First-In-First-Out (FIFO) data structure. In a FIFO data structure, the first element added to the queue will be the first one to be removed. This is equivalent to the requirement that once a new element is added, all elements that were added before have to be removed before the new element can be removed. Often a peek or front operation is also entered, returning the value of the front element without dequeuing it. A queue is an example of a linear data structure, or more abstractly a sequential collection."
Queues provide services in computer science,transport, and operations research where various entities such as data, objects, persons, or events are stored and held to be processed later. In these contexts, the queue performs the function of a buffer.
Deque 和vector內存管理不同: 大塊分配內存！屬于雙向隊列, 和vector類似, 新增加:
1.push_front 在頭部插入一個元素
2.pop_front 在頭部彈出一個元素
對于deque和vector來說，盡量少用erase(pos)和erase(beg,end)。因為這在中間刪除數據后會導致后面的數據向前移動，從而使效率低下。
Some API :
2》Stack
實際底層也是使用Deque實現, 但也可以用實際制定容器Container
先進后出結構? 只有一個出口 ，且只能訪問頂端元素, 不允許遍歷 支持操作:?
1.push增加元素
2.pop移除元素
3.top獲取頂端元素
3.Queue
queues are a type of container adaptor, specifically designed to operate in a FIFO context (first-in first-out), where elements are inserted into one end of the container and extracted from the other.
queues are implemented as containers adaptors, which are classes that use an encapsulated object of a specific container class as its? underlying container, providing a specific set of member functions to access its elements. Elements are pushed into the"back"of the specific container andpopped from its"front".
實際底層使用Deque實現, 但也可以實際制定容器Container
先進先出結構, 兩個出口 ，不允許遍歷 ,支持操作:
1.push增加元素
2.pop移除元素
3.front獲取最前端元素
4.back獲取最后的元素
4. Map
關聯容器, 存儲對象為key/value pair ,但不允許重復 key ，map存儲對象必須具備可排序性
類的聲明：
template < class _Kty, class _Ty, class _Pr = lass<_Kty>, class _Alloc = allocator < pair < const _Kty, _Ty> > >? class map{…………};
1, 兩個> > 之間是有一個空格
2, 其中默認使用lass定義排序行為, 所以我們可以自定義排序行為 - 仿函數實現
3, 注意各種class的順序!!! 注意排序所使用的可以是在哪里!!!
a.定義一個類
struct Employee{
? ? Employee(string& s1): Name(s1){}
? ? string Name;
};b.定義一個仿函數
struct ReverseId: public std::binary_function< int, int, bool>{
? ? bool operator() (const int& key1, const int& key2) const {
? ? return (key1 <= key2) ? false : true;
? ? }
};
仿函數就是要重載()小括號操作符! ! !使用例子:
c. 構建一個序列:
std::pair < int, Employee> item[3] = {
? ? std::make_pair(1, Employee(“Tom”)),
std::make_pair(2, Employee(“Azm”)),
std::make_pair(3, Employee(“Jack”)),
};d.定義一個map,是一個按照我們制定排序方法的map
std::map < int, Employee, ReverseId > map1(item, item+3);e. 在map中插入元素
方法1 : map1.insert(std::make_pair(4,Employee(“Jason”)));
方法2 : map1[5] = Employee(“Hellon”);f. 刪除元素
std::map < int, Employee>::iterator it = map1.begin();
map1.erase(it);g. 使用[]操作符存取元素
Employee& e = map1[14];
e.SetName(“Wason”);
5. Multimap
Multimaps are associative containers that store elements formed by a combination of akey valueand amapped value, following a specific order, and where multiple elements can have equivalent keys.
它類似map的關聯容器 ，允許key重復！
查找
1. 直接找到每種鍵值的所有元素的第一個元素的游標
通過函數：lower_bound( const keytype& x ), upper_bound( const keytype& x ) 可以找到比指定鍵值x的小的鍵值的第一個元素和比指定鍵值x大的鍵值的第一個元素。返回值為該元素的游標。
細節：當到達鍵值x已經是最大時，upper_bound返回的是這個multimap的end游標。同理，當鍵值x已經是最小了，lower_bound返回的是這個multimap的begin游標。
2. 指定某個鍵值，進行遍歷
可以使用上面的lower_bound和upper_bound函數進行游歷，也可以使用函數equal_range。其返回的是一個游標對。游標對pair::first是由函數lower_bound得到的x的前一個值，游標對pair::second的值是由函數upper_bound得到的x的后一個值。
multimap<int ,int > a;
a.insert(pair(1,11));
a.insert(pair(1,12));
a.insert(pair(1,13));
a.insert(pair(2,21));
a.insert(pair(2,22));
a.insert(pair(3,31));
a.insert(pair(3,32));
multimap::iterator p_map;
pair::iterator, multimap::iterator> ret;
for(p_map = a.begin() ; p_map != a.end();) {?
cout";
ret = a.equal_range(p_map->first);
for(p_map = ret.first; p_map != ret.second; ++p_map)
cout<<""<< (*p_map).second;
cout<<endl;
}
std::multimap < int, Employee, ReverseId > mm1(item, item+3);
#如果插入一個重復的key=1的key:
map1.insert(std::make_pair(4,Employee(“Peter”)));
#則:?
mm1.count(4)? //得到2? 表名其中有兩個key為4的元素
6.Set
Sets are containers that store unique elements following a specific order.
In aset, the value of an element also identifies it (the value is itself thekey, of typeT), and each value must be unique. The value of the elements in asetcannot be modified once in the container (the elements are always const), but they can be inserted or removed from the container.
set初始化:
struct Programmer{
Programmer(const int id, const std::wstring name):
Id(id), Name(name){? }
void Print() const
{
std::wcout<
}
int Id;
std::wstring Name;
};
set相關算法:?
1. set_union
std::set < Programmer, ProgrammerIdGreater > dest;
std::insert_iterator < std::set < Programmer, ProgrammerIdGreater > > ii(dest, dest.begin());
std::set_union(ps1.begin(), ps1.end(), ps2.begin(), ps2.end(), ii, ProgrammerIdGreater());
將會把ps1和ps2合并到dest當中,這里將會依照給出的排序規則進行排序!
2, set_intersection
std::set < Programmer, ProgrammerIdGreater > dest;
std::insert_iterator < std::set < Programmer, ProgrammerIdGreater > > ii(dest, dest.begin());
std::set_intersection(ps1.begin(), ps1.end(), ps3.begin(), ps3.end(), ii, ProgrammerIdGreater());
將會把ps1和ps3中全部重復的元素提取出來放在dest中! 這里將會依照給出的排序規則進行排序!
The sharing of knowledge, the spirit of encouragement.
By Joel Jiang (江東敏)
