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C++ Program to Represent Graph Using Adjacency List
The adjacency list representation of a graph is linked list representation. In this representation we have an array of lists The array size is V. Here V is the number of vertices. In other words, we can say that we have an array to store V number of different lists. If a list header is vertex u, then it signifies that it will hold all of the adjacent vertices of u.
The complexity of Adjacency List representation
This representation takes O(V+2E) for undirected graph, and O(V+E) for directed graph. If the number of edges are increased, then the required space will also be increased.
Input:
Output:
Algorithm
add_edge(adj_list, u, v)
Input − The u and v of an edge {u,v}, and the adjacency list
Output − Adjacency List of the graph G
Begin Append v into the list at index u Append u into the list at index v End
Example Code
#include<iostream>
#include<list>
#include<iterator>
using namespace std;
void displayAdjList(list<int> adj_list[], int v) {
for(int i = 0; i<v; i++) {
cout << i << "--->";
list<int> :: iterator it;
for(it = adj_list[i].begin(); it != adj_list[i].end(); ++it) {
cout << *it << " ";
}
cout << endl;
}
}
void add_edge(list<int> adj_list[], int u, int v) { //add v into the list u, and u into list v
adj_list[u].push_back(v);
adj_list[v].push_back(u);
}
main(int argc, char* argv[]) {
int v = 6; //there are 6 vertices in the graph
//create an array of lists whose size is 6
list<int> adj_list[v];
add_edge(adj_list, 0, 4);
add_edge(adj_list, 0, 3);
add_edge(adj_list, 1, 2);
add_edge(adj_list, 1, 4);
add_edge(adj_list, 1, 5);
add_edge(adj_list, 2, 3);
add_edge(adj_list, 2, 5);
add_edge(adj_list, 5, 3);
add_edge(adj_list, 5, 4);
displayAdjList(adj_list, v);
}Output
0--->4 3 1--->2 4 5 2--->1 3 5 3--->0 2 5 4--->0 1 5 5--->1 2 3 4
Updated on: 30-Jul-2019
3K+ Views
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