addition: add and connect vertex

src/graph.c

@@ -1,8 +1,10 @@
 #include "graph.h"
 #include "arraylist.h"
 #include <inttypes.h>
+#include <stddef.h>
 #include <stdint.h>
 #include <stdlib.h>
+#include <sys/ucontext.h>
 
 struct Vertex {
     ArrayList *edges;
@@ -50,5 +52,49 @@ GraphErr graph_destroy(Graph **graph) {
 
     arraylist_destroy(&(*graph)->vertices);
 
+    *graph = NULL;
+
+    return GRAPH_OK;
+}
+
+GraphErr graph_add_vertex(Graph *graph) {
+    if (graph == NULL) {
+        return GRAPH_NULL_ARG;
+    }
+
+    Vertex new_vertex = {.edges = arraylist_init(16, sizeof(Edge))};
+
+    arraylist_push_back(graph->vertices, &new_vertex);
+
+    return GRAPH_OK;
+}
+
+GraphErr graph_connect_vertex(
+    Graph *graph,
+    size_t node1,
+    size_t node2,
+    size_t weight) {
+    if (graph == NULL) {
+        return GRAPH_NULL_ARG;
+    }
+
+    size_t vertex_count = arraylist_size(graph->vertices);
+    if (node1 >= vertex_count || node2 >= vertex_count) {
+        return GRAPH_VERTEX_NOT_FOUND;
+    }
+
+    Edge new_edge = {.to = node2, .weight = weight};
+    Vertex vertex1;
+    Vertex vertex2;
+    arraylist_get(graph->vertices, node1, &vertex1);
+    arraylist_get(graph->vertices, node2, &vertex2);
+
+    arraylist_push_back(vertex1.edges, &new_edge);
+
+    if (graph->type == GRAPH_UNDIRECTED) {
+        Edge inverse_edge = {.to = node1, .weight = weight};
+        arraylist_push_back(vertex2.edges, &inverse_edge);
+    }
+
     return GRAPH_OK;
 }