addtition: graph create

src/graph.c

@@ -2,6 +2,7 @@
 #include "arraylist.h"
 #include <inttypes.h>
 #include <stdint.h>
+#include <stdlib.h>
 
 struct Vertex {
     ArrayList *edges;
@@ -16,3 +17,20 @@ struct Graph {
     ArrayList *vertices;
     GraphType type;
 };
+
+Graph *graph_create(GraphType type) {
+    Graph *graph = malloc(sizeof(Graph));
+    if (graph == NULL) {
+        return NULL;
+    }
+
+    graph->type = type;
+    graph->vertices = arraylist_init(64, sizeof(Vertex));
+
+    if (graph->vertices == NULL) {
+        free(graph);
+        return NULL;
+    }
+
+    return graph;
+}