//DFS algorithm
int *visited
int order;

dfs(graph g){
    visited = malloc(sizeof(int)*nV(g));
    order = 1;
    dfsR(g, 0);
}

dfsR(graph g, vertex v){
    visited[v] = order++;
    vertex w;
    for(w=0; w<nV(g); w++){
        if(!hasEdge(g,v,w)){
            continue;
        }
        if(!visited[w]){
            dfsR(g, w);
        }
    }
}

//return 1 if path exists between 'a' and 'b', 0 if path doesn't exist
int pathExists(graph g, vertex a, vertex b){

}