#include <iostream>
using namespace std;

class Solution {
    set<string> visited;
    string hostname;
    HtmlParser *html_parser;
    mutex mutex_;

    string getHostname(string url) {
        auto idx = url.find('/', 7); // http//:
        return (idx != string::npos ? url.substr(0, idx) : url);
    }
public:
    void crawlUtil(string curr_url) {
        vector<thread*> threadPool;
        for (string next : html_parser->getUrls(curr_url)) {
            lock_guard<mutex> lock(mutex_);
            if (getHostname(next) == hostname &&
                !visited.count(next)) {
                visited.insert(next);
                threadPool.push_back(
                    new thread(&Solution::crawlUtil, this, next));
            }
        }
        for (auto& t : threadPool) {
            t->join();
            delete t;
        }
    }      

    vector<string> crawl(string startUrl, HtmlParser htmlParser) {
        hostname = getHostname(startUrl);        
        html_parser = &htmlParser;
        visited.insert(startUrl);
        
        std::thread mainThread(&Solution::crawlUtil, this, startUrl);
        mainThread.join();
		
        return vector<string>(visited.begin(), visited.end());
    }
};

int main() 
{
    cout << "Hello, World!";
    return 0;
}
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Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}