#include <iostream>
#include <vector>
#include <queue>
#include <climits>
#include <chrono>

using namespace std;
using namespace std::chrono;

// Structure to represent a node in the graph
struct Node {
    int vertex;
    int weight;
};

// Comparator for priority queue
struct Compare {
    bool operator()(const Node& a, const Node& b) {
        return a.weight > b.weight;
    }
};

// Function to perform Prim's Algorithm
void prim(vector<vector<int>>& graph, int numNodes) {
    vector<bool> visited(numNodes, false);
    priority_queue<Node, vector<Node>, Compare> pq;
    int totalWeight = 0;

    // Start with node 0
    pq.push({0, 0});

    auto start = high_resolution_clock::now(); // Start measuring time

    while (!pq.empty()) {
        int u = pq.top().vertex;
        int w = pq.top().weight;
        pq.pop();

        if (visited[u])
            continue;

        visited[u] = true;
        totalWeight += w;

        for (int v = 0; v < numNodes; ++v) {
            if (graph[u][v] != 0 && !visited[v]) {
                pq.push({v, graph[u][v]});
            }
        }
    }

    auto end = high_resolution_clock::now(); // End measuring time

    auto duration = duration_cast<milliseconds>(end - start);
    double durationInSeconds = duration.count() / 1000.0;

    cout << "Total weight of MST: " << totalWeight << endl;
    cout << "Execution time: " << durationInSeconds << " seconds" << endl;
}

int main() {
    int numNodes = 5;
    // Example graph represented as an adjacency matrix
    vector<vector<int>> graph = {
        {0, 2, 0, 6, 0},
        {2, 0, 3, 8, 5},
        {0, 3, 0, 0, 7},
        {6, 8, 0, 0, 9},
        {0, 5, 7, 9, 0}
    };

    prim(graph, numNodes);

    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
}