Graph implementation using STL for competitive programming | Set 2 (Weighted graph)

In Set 1, unweighted graph is discussed. In this post, weighted graph representation using STL is discussed. The implementation is for adjacency list representation of weighted graph.

We use two STL containers to represent graph:

The idea is to use a vector of pair vectors. Below code implements the same.

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// C++ program to represent undirected and weighted graph
// using STL. The program basically prints adjacency list
// representation of graph
#include <bits/stdc++.h>
using namespace std;
  
// To add an edge
void addEdge(vector <pair<int, int> > adj[], int u,
                                     int v, int wt)
{
    adj[u].push_back(make_pair(v, wt));
    adj[v].push_back(make_pair(u, wt));
}
  
// Print adjacency list representaion ot graph
void printGraph(vector<pair<int,int> > adj[], int V)
{
    int v, w;
    for (int u = 0; u < V; u++)
    {
        cout << "Node " << u << " makes an edge with \n";
        for (auto it = adj[u].begin(); it!=adj[u].end(); it++)
        {
            v = it->first;
            w = it->second;
            cout << "\tNode " << v << " with edge weight ="
                 << w << "\n";
        }
        cout << "\n";
    }
}
  
// Driver code
int main()
{
    int V = 5;
    vector<pair<int, int> > adj[V];
    addEdge(adj, 0, 1, 10);
    addEdge(adj, 0, 4, 20);
    addEdge(adj, 1, 2, 30);
    addEdge(adj, 1, 3, 40);
    addEdge(adj, 1, 4, 50);
    addEdge(adj, 2, 3, 60);
    addEdge(adj, 3, 4, 70);
    printGraph(adj, V);
    return 0;
}
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Output:



Node 0 makes an edge with 
    Node 1 with edge weight =10
    Node 4 with edge weight =20

Node 1 makes an edge with 
    Node 0 with edge weight =10
    Node 2 with edge weight =30
    Node 3 with edge weight =40
    Node 4 with edge weight =50

Node 2 makes an edge with 
    Node 1 with edge weight =30
    Node 3 with edge weight =60

Node 3 makes an edge with 
    Node 1 with edge weight =40
    Node 2 with edge weight =60
    Node 4 with edge weight =70

Node 4 makes an edge with 
    Node 0 with edge weight =20
    Node 1 with edge weight =50
    Node 3 with edge weight =70

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