How do I implement graphs in C using data structures?

How do I implement graphs in C using data structures?

To implement graphs in C, you can use adjacency lists or adjacency matrices. Which one would you like to know more about?

Can you explain the adjacency list method?

Sure! An adjacency list uses an array of lists. Each index represents a vertex, and the list at that index contains all adjacent vertices.

How do I create a graph using an adjacency list?

You can define a struct for the adjacency list and then create functions to add edges and display the graph. Would you like a code example?

Yes, please provide a code example!

Here's a simple example:

#include <stdio.h>
#include <stdlib.h>

struct Node {
    int vertex;
    struct Node* next;
};

struct Graph {
    int numVertices;
    struct Node** adjLists;
};

struct Graph* createGraph(int vertices) {
    struct Graph* graph = malloc(sizeof(struct Graph));
    graph->numVertices = vertices;
    graph->adjLists = malloc(vertices * sizeof(struct Node*));
    for (int i = 0; i < vertices; i++)
        graph->adjLists[i] = NULL;
    return graph;
}

void addEdge(struct Graph* graph, int src, int dest) {
    struct Node* newNode = malloc(sizeof(struct Node));
    newNode->vertex = dest;
    newNode->next = graph->adjLists[src];
    graph->adjLists[src] = newNode;
}

void printGraph(struct Graph* graph) {
    for (int v = 0; v < graph->numVertices; v++) {
        struct Node* temp = graph->adjLists[v];
        printf("Vertex %d: ", v);
        while (temp) {
            printf("-> %d ", temp->vertex);
            temp = temp->next;
        }
        printf("\n");
    }
}

This code creates a graph and adds edges between vertices.