 #include <bits/stdc++.h>

using namespace std;

void extractIntegerfromstr(string str, int &i, int &j)
{
    stringstream s;
    string temp;
    int num;

    s << str;
    num = 0;

    while (!s.eof())
    {
        s >> temp;

        if (num == 0 && stringstream(temp) >> i)
        {
            num = 1;
        }
        else if (num == 1 && stringstream(temp) >> j)
        {
            num++;
        }
        temp = "";
    }
}

class Graph
{
    int V;
    vector<vector<int>> adj;

public:
    Graph(int V);
    void addEdge(int v, int w);
    bool isReachable(int start, int end);
    void graphprint();
    int degreecentrality1(int &max);
    int degreecentrality2(int &max);
    int Closeness_centrality_1(int &max);
    void DFS(int current, int &cnt, vector<int> &visited, vector<int> &duringdfs);
    int Closeness_centrality_2(int &max);
};

Graph::Graph(int V)
{
    this->V = V;
    adj.resize(V + 1);
}

void Graph::addEdge(int i, int j)
{
    if (find(adj[i].begin(), adj[i].end(), j) == adj[i].end() && i != j)
        adj[i].push_back(j);
}

void Graph::graphprint()
{
    for (int i = 0; i < adj.size(); i++)
    {
        cout << i << " ";
        for (auto j = 0; j < adj[i].size(); j++)
        {
            cout << " --> " << adj[i].at(j);
        }
        cout << endl;
    }
}

int Graph ::degreecentrality1(int &max)
{
    vector<int> size;

    for (auto i = 1; i < adj.size(); i++)
    {
        size.push_back(adj[i].size());
    }
    max = *max_element(size.begin(), size.end());

    int node = distance(size.begin(), max_element(size.begin(), size.end())) + 1;

    return node;
}
int Graph ::degreecentrality2(int &max)
{
    vector<int> degree;

    degree.resize(V + 1);

    for (auto i = 1; i <= V; i++)
    {
        for (int j = 0; j < adj[i].size(); j++)
        {
            degree[i]++;
            degree[adj[i].at(j)]++;
        }
    }

    max = *max_element(degree.begin(), degree.end());
    for (int i = 0; i < V + 1; i++)
    {
        if (degree[i] == max)
            return i;
    }

    return -1;
}
bool Graph::isReachable(int s, int d)
{
    if (s == d)
        return true;

    bool *visited = new bool[V];
    for (int i = 0; i < V; i++)
        visited[i] = false;

    list<int> queue;

    visited[s] = true;
    queue.push_back(s);

    vector<int>::iterator i;

    while (!queue.empty())
    {
        s = queue.front();
        queue.pop_front();

        for (i = adj[s].begin(); i != adj[s].end(); ++i)
        {
            if (*i == d)
                return true;

            if (!visited[*i])
            {
                visited[*i] = true;
                queue.push_back(*i);
            }
        }
    }

    return false;
}

int Graph ::Closeness_centrality_1(int &max)
{
    int nodesconectivity[V + 1] = {0};
    for (int i = 1; i <= V; i++)
    {
        for (int j = 1; j <= V; j++)
        {
            if (isReachable(i, j))
            {
                nodesconectivity[i]++;
            }
        }
    }
    max = *max_element(nodesconectivity, nodesconectivity + V + 1);

    for (int i = 1; i < V + 1; i++)
    {
        if (nodesconectivity[i] == max)
            return i;
    }

    return -1;
}

void Graph ::DFS(int current, int &count, vector<int> &visited, vector<int> &duringdfs)
{
    visited[current] = 1;

    ++count;

    duringdfs.push_back(current);
    for (auto &child : adj[current])
    {
        if (visited[child] == 0)
        {
            DFS(child, count, visited, duringdfs);
        }
    }
}

int Graph ::Closeness_centrality_2(int &max)
{
    vector<int> visited(V + 1, 0);
    vector<int> ans(V + 1);
    vector<int> duringdfs;

    for (int i = 1; i <= V; ++i)
    {
        duringdfs.clear();
        int count = 0;

        if (visited[i] == 0)
        {
            count = 0;
            DFS(i, count, visited, duringdfs);
        }

        for (auto &x : duringdfs)
        {
            ans[x] = count;
        }
    }

    int max2 = *max_element(ans.begin(), ans.begin() + V + 1);
    max = max2;
    int index = distance(ans.begin(), find(ans.begin(), ans.end(), max2));

    return index;
}

int main()
{

    string str;
    int i, j, c;
    int maxnode1, maxnode2, max;
    int n;
    cout << "Enter total number of nodes\n";
    cin >> n;
    Graph g(n);

    int number;
    cout << "Enter total number of connection\n";
    cin >> number;

    fflush(stdin);

    for (int k = 0; k < number; k++)
    {
        getline(cin, str);
        extractIntegerfromstr(str, i, j);
        g.addEdge(i, j);
    }

    g.graphprint();

    cout << "Most influencler node according to Degree Centrality Method\n";
    maxnode1 = g.degreecentrality1(max);
    cout << "If we considered Only one side of influence then the node which has most influence power is " << maxnode1 << " which is connected to " << max << " nodes" << endl;
    maxnode2 = g.degreecentrality2(max);
    cout << "If we considered both side of influence then the node which has most influence power is " << maxnode2 << " which is connected to " << max << " nodes" << endl;

    cout << endl;

    cout << "Most influencler node according to Closeness Centrality Method\n";
    int met2 = g.Closeness_centrality_1(max);
    cout << "If we considered Only one side of influence then the node which has most influence power is " << met2 << " which is connected to " << max << " nodes" << endl;
    int ans2 = g.Closeness_centrality_2(max);
    cout << "If we considered both side of influence then the node which has most influence power is " << ans2 << " which is connected to " << max << " nodes" << endl;

return 0;
}

created 3 years ago by 2021 01226

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Read inputs from stdin

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#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
}