addition: destroy graph

include/graph.h

@@ -10,7 +10,8 @@ typedef struct Edge Edge;
 typedef enum {
     GRAPH_OK,
     GRAPH_BAD_ALLOC,
-    GRAPH_NOT_FOUND,
+    GRAPH_VERTEX_NOT_FOUND,
+    GRAPH_NULL_ARG,
 } GraphErr ;
 
 typedef enum {
@@ -19,7 +20,7 @@ typedef enum {
 } GraphType;
 
 Graph *graph_create(GraphType type);
-GraphErr graph_destroy(Graph *graph);
+GraphErr graph_destroy(Graph **graph);
 
 GraphErr graph_add_vertex(Graph *graph);
 

src/graph.c

@@ -34,3 +34,21 @@ Graph *graph_create(GraphType type) {
 
     return graph;
 }
+
+GraphErr graph_destroy(Graph **graph) {
+    if (graph == NULL || *graph) {
+        return GRAPH_NULL_ARG;
+    }
+
+    size_t vertex_count = arraylist_size((*graph)->vertices);
+
+    for (size_t i = 0; i < vertex_count; i++) {
+        Vertex vertex;
+        arraylist_get((*graph)->vertices, i, &vertex);
+        arraylist_destroy(&vertex.edges);
+    }
+
+    arraylist_destroy(&(*graph)->vertices);
+
+    return GRAPH_OK;
+}