Implementation of Depth First Search DFS in C

HERE IS THE CODE..

#include<stdio.h>

#include<stdlib.h>

struct node {

    int data;

    struct node *next;

};

struct node *nodeList[20];

void dfs(int, int*);

void insert(int, int);

void main() {

    int numberOfVertices,numberOfEdges, i, j, v1, v2, visited[20];

    printf("Enter the number of vertices\n");

    scanf("%d", &numberOfVertices);

    for (i=0;i<=numberOfVertices;i++) {

        visited[i] = 0;

        nodeList[i]=NULL;

    }

    printf("Enter the number of edges\n");

    scanf("%d", &numberOfEdges);

    for (i=0;i<numberOfEdges;i++) {

        printf("Enter the edges\n");

        scanf("%d %d", &v1, &v2);

        insert(v1, v2);

    }

    dfs(1, visited);

}



// vertax is v1 and it points to v2 so add v2 in linked list of node v1

// ie. add v2 to nodeList[v1]

void insert(int v1, int v2) {

    struct node *temp2;

    struct node *temp = (struct node*)malloc(sizeof(struct node));

    temp->data = v2;

    temp->next = NULL;



    if (nodeList[v1]==NULL) {

        nodeList[v1] = temp;

    } else {

        temp2 = nodeList[v1];

        while(temp2->next != NULL) {

            temp2 = temp2->next;

        }

        temp2->next = temp;

    }

}



// start_node is the vertax from which dfs traversal starts

void dfs(int start_node, int *visited) {

    struct node *temp;

    if (visited[start_node] != 1) {

        printf("%d\t", start_node);

        visited[start_node] = 1;

    }

    temp = nodeList[start_node];

    while (temp != NULL) {

        if (visited[temp -> data] != 1) {

            dfs(temp->data, visited);

        }

        temp = temp->next;

    }

}