Supplements algorithm [4] - STL usage

The main priority queues and strings bb about it. Oh, there is bitset.

Priority Queue

• It is easy to define: priority_queue<int> pq;
• The interior is a heap.

Basic Operations

• pq.top()Take the top of the stack elements; (no front()way!)
• pq.push(x) insert;
• pq.pop() Delete (delete the top of the heap);
• pq.empty() Judgment is empty.

Custom priority

• The maximum heap: priority_queue<int> pq;
• Minimum heap: priority_queue< int, vector<int>, greater<int> > pq;
• There are actually custom-priority cmpmethod (the first priority of the biggest teams):

  Supplements algorithm [4] - STL usage large column ody>

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  struct { BOOL operator () ( const int A, const int B) const { return A> B; }};The priority_queue < int , Vector < int >, CMP> PQ; // this time is the minimum heap

example

• One hundred training 4078: http://bailian.openjudge.cn/practice/4078/

String

The definition easier: string s;

Basic Operations

• s.size() String length (starting with index 0);
• s.substr(a, n) Substring configuration, a is the first subscript character, n is an substring character length;
• s'find(it1, it2, x)Pointer it1and it2find intermediate character x; ( s.find(x)entire slookup x)
• s.erase(a)Removing elements, A looks like a pointer, and can be findcombined with the removal of the specified character, such as s.erase(std::find(s.begin(), s.end(), ' '));removing any spaces;
• s.empty() It determines whether null;
• Support push_backand pop_back;
  
• Support +, =and ==operations.

Traversal operation

• You can auto it = s.begin(); it != s.end(); it++traverse;
• But I generally use int i = 0; i < s.size(); i++to traverse.

And digital conversion

String-to-digital

• stoi, stol, stoll: String to Integer;
• stof, stod, stold: String float switch;

Digital to String

• to_stringDirect turn into std::string.

Bit vector

definition: bitset<length> b(value);

Basic Operations

• Bit computing support &, ^, <<, >>and so on;
• to_string() Into a string;
• to_ulong(), to_ullong()Is converted to an unsigned integer;
• flip(i)The i-th bit inverse, index from 0. flip()All bitwise.