#include <iostream>
#include <vector>
#include <queue>
#include <omp.h>

// Structure to represent a graph
struct Graph {
    int numVertices;
    std::vector<std::vector<int>> adjacencyList;
};

// Breadth-First Search
void parallelBFS(const Graph& graph, int startVertex) {
    std::vector<bool> visited(graph.numVertices, false);
    std::queue<int> bfsQueue;
    bfsQueue.push(startVertex);
    visited[startVertex] = true;

    #pragma omp parallel
    {
        while (!bfsQueue.empty()) {
            #pragma omp for
            for (int i = 0; i < bfsQueue.size(); ++i) {
                int currentVertex = bfsQueue.front();
                bfsQueue.pop();
                std::cout << currentVertex << " ";  // Process current vertex
                // Enqueue adjacent unvisited vertices
                for (int neighbor : graph.adjacencyList[currentVertex]) {
                    if (!visited[neighbor]) {
                        visited[neighbor] = true;
                        bfsQueue.push(neighbor);
                    }
                }
            }
        }
    }
}

int main() {
    Graph graph;
    // Initialize the graph and populate the adjacency list

    // Example graph with 6 vertices
    graph.numVertices = 6;
    graph.adjacencyList.resize(graph.numVertices);

    // Add edges to the adjacency list
    graph.adjacencyList[0] = {1, 2};
    graph.adjacencyList[1] = {0, 2, 3, 4};
    graph.adjacencyList[2] = {0, 1, 4};
    graph.adjacencyList[3] = {1, 4, 5};
    graph.adjacencyList[4] = {1, 2, 3, 5};
    graph.adjacencyList[5] = {3, 4};

    // Perform parallel BFS
    parallelBFS(graph, 0);

    return 0;
}

C++ Online Compiler

Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++ and start coding!

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
}