Perform a recursive DFS traversal over a graph represented using an adjacency list.
Difficulty level
This exercise is mostly suitable for students
#include<stdio.h>
#include<stdlib.h>
typedef struct node {
int vertexNumber;
struct node * next;
} node;
typedef struct {
int V;
int E;
node** Adj; //array of linked list
} Graph;
Graph* adjacencyList() {
int i, x, y;
node * temp, *temp2;
Graph* G=(Graph*) malloc(sizeof(Graph));
printf("Enter the number of Vertices: ");
scanf("%d", &G->V);
printf("Enter the number of Edges: ");
scanf("%d", &G->E);
G->Adj = (node **)malloc(G->V * sizeof(node));
for (i = 0; i < G->V; i++) {
G->Adj[i] = (node *)malloc(G->V * sizeof(node));
G->Adj[i]->vertexNumber = i;
G->Adj[i]->next = NULL;
}
for (i = 0; i < G->E; i++) {
printf("Enter the edge: ");
scanf("%d %d", &x,&y);
temp = (node*)malloc(sizeof(node));
temp->vertexNumber = y;
temp->next = NULL;
temp2 = G->Adj[x];
while (temp2->next != NULL)
temp2 = temp2->next;
temp2->next = temp;
}
return G;
}
void DFSTraversal(Graph* G, int index, int Visited[])
{
node * head;
head = G->Adj[index]->next;
printf("%d ",index);
while(head)
{
if(!Visited[head->vertexNumber])
{
Visited[head->vertexNumber]=1;
DFSTraversal(G, head->vertexNumber, Visited);
}
head=head->next;
}
}
void DFS(Graph *G) {
int i;
int *Visited;
Visited = (int *)malloc(G->V * sizeof(int));
for (i = 0; i < G->V; i++)
Visited[i] = 0;
// this loop is required if the graph has more than one component
for (i = 0; i < G ->V; i++)
if (!Visited[i])
{
Visited[i] = 1;
DFSTraversal(G, i, Visited);
}
}
void test() {
Graph *G = adjacencyList();
DFS(G);
}
int main()
{
test();
return 0;
}
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