How to mark a vertex has been visited in graph

I am implementing graph structure for my path finding in a maze program. In some operation like: traversing graph, free the graph (which is malloc-ed before, or use breadth first search,... It is require to check if a vertex is visited or not.

This is vertex and edge struct:

typedef struct graph
{
    // val just use to label the vertex
    int val;

    // since the maze just has 4 directions,
    // I simplify vertex to just point to 4 other vertices
    edge up;
    edge down;
    edge left;
    edge right;
}vertex;

typedef struct Edge
{
    int weight;
    vertex *neighbour;
    bool visited;
}edge;

I have thought about 2 solutions. The first is add bool visited; in vertex or edge struct and initialize it to false, but it just able to use 1 time, because I don't know how to reinitialize the visited. The second approach is make a link list, put the visited vertex in that list and check for visited vertex in that list when required. But it costs so much work when there are hundred of vertices.

So what is the good mechanism to check a vertex is visited? What is the better way to implement this problem?