#include <iostream>
#include <vector>
#include <queue>
#include <unordered_map>
#include <unordered_set>
#include <cmath>
#include <climits>
#include <algorithm>
using namespace std;

// Function to check if a subset of companies satisfies the distance constraint
bool isValidSubset(const vector<int>& companies, const unordered_map<int, vector<pair<int, int>>>& graph, int minDist, const vector<int>& nodeCompanies) {
    unordered_set<int> nodes;

    // Gather all nodes owned by the selected companies
    for (int company : companies) {
        for (size_t i = 0; i < nodeCompanies.size(); ++i) {
            if (nodeCompanies[i] == company) nodes.insert(i + 1);
        }
    }

    // Check pairwise distances between nodes
    for (int node : nodes) {
        queue<pair<int, int>> q; // Pair of {current node, distance from start}
        unordered_set<int> visited;
        q.push({node, 0});
        visited.insert(node);

        // Perform BFS to calculate distances from the current node
        while (!q.empty()) {
            auto [current, dist] = q.front();
            q.pop();

            // Check neighbors
            for (const auto& [neighbor, weight] : graph.at(current)) {
                if (!visited.count(neighbor)) {
                    if (nodes.count(neighbor) && dist + weight < minDist) {
                        return false; // Distance requirement violated
                    }
                    visited.insert(neighbor);
                    q.push({neighbor, dist + weight});
                }
            }
        }
    }

    return true;
}

// Main function to calculate the number of valid subsets
int countValidSubsets(int graph_node, const vector<int>& graph_from, const vector<int>& graph_to,
                      const vector<int>& weights, int minDist, const vector<int>& companies) {
    // Step 1: Build the graph
    unordered_map<int, vector<pair<int, int>>> graph;
    for (size_t i = 0; i < graph_from.size(); ++i) {
        int u = graph_from[i], v = graph_to[i], w = weights[i];
        graph[u].push_back({v, w});
        graph[v].push_back({u, w});
    }

    // Step 2: Generate subsets of companies
    int companyCount = *max_element(companies.begin(), companies.end());
    int validSubsetCount = 0;

    for (int mask = 1; mask < (1 << companyCount); ++mask) {
        vector<int> subset;
        for (int i = 0; i < companyCount; ++i) {
            if (mask & (1 << i)) {
                subset.push_back(i + 1); // Convert 0-based index to company number
            }
        }

        // Step 3: Check if the subset is valid
        if (isValidSubset(subset, graph, minDist, companies)) {
            ++validSubsetCount;
        }
    }

    return validSubsetCount;
}

int main() {
    // Hardcoded inputs
    int graph_node = 4; // Number of nodes
    vector<int> graph_from = {1,2,1,1}; // From nodes
    vector<int> graph_to = {2,3,3,4};   // To nodes
    vector<int> weights = {2,1,3,10};    // Weights of edges
    int minDist = 2;                       // Minimum distance requirement
    vector<int> companies = {1,2,3,2};  // Company assigned to each node

    // Count the valid subsets
    int result = countValidSubsets(graph_node, graph_from, graph_to, weights, minDist, companies);
    cout << "Number of valid subsets: " << result << endl;

    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
}