diff --git a/utils/dijkstra.py b/utils/dijkstra.py
index 846027b..8f8ba8d 100644
--- a/utils/dijkstra.py
+++ b/utils/dijkstra.py
@@ -1,86 +1,88 @@
 from math import inf
+from typing import Iterator, Optional
 
-class Edge:
-
-    length = 0
-
-    def __init__(self, start, end, length):
-        self.length = length
-        self.start = start
-        self.end = end
 
 class Node:
+    def __init__(self, x: int, y: int):
+        self.x: int = x
+        self.y: int = y
+
+
+class Edge:
+    def __init__(self, start: int, end: int, length: float):
+        self.length: float = length
+        self.start: int = start
+        self.end: int = end
 
-    def __init__(self, xpos, ypos):
-        self.xpos = xpos
-        self.ypos = ypos
 
 class Graph:
-
     def __init__(self):
-        self.edges = list()
-        self.nodes = list()
+        self.edges: list[Edge] = []
+        self.nodes: list[Node] = []
 
-    def add_node(self, xpos, ypos):
-        self.nodes.append(Node(xpos, ypos))
-    
-    def add_edge(self, start_index, end_index, length):
+    def add_node(self, x: int, y: int) -> None:
+        self.nodes.append(Node(x, y))
+
+    def add_edge(self, start_index: int, end_index: int, length: float) -> None:
         self.edges.append(Edge(start_index, end_index, length))
 
+    def edges_adjacent_to(self, node_i: int) -> Iterator[Edge]:
+        return filter(lambda e: e.start == node_i or e.end == node_i, self.edges)
 
-def Dijkstra(graph, source_index, target_index):
+    def dijkstra(self, source_index: int, target_index: int) -> Optional[list[int]]:
+        n = len(self.nodes)
 
-    n = len(graph.nodes)
+        if source_index < 0 or source_index >= n:
+            return None
 
-    if (target_index >= n):
-        return None
+        if target_index < 0 or target_index >= n:
+            return None
 
-    unvisited = list(range(n))
+        unvisited = list(range(n))
 
-    distances_from_start = [inf] * n
-    distances_from_start[source_index] = 0
+        distances_from_start = [inf] * n
+        distances_from_start[source_index] = 0
 
-    node_sequences = [list() for i in range(n)]
-    node_sequences[source_index] = [source_index]
+        node_sequences = [[] for _ in range(n)]
+        node_sequences[source_index] = [source_index]
 
-    while(True):
-        try:
-            current_index = min(unvisited, key = lambda i: distances_from_start[i])
-        except ValueError:
-            break
-        
-        if current_index == target_index:
-            break
+        while True:
+            current_index = min(unvisited, key=lambda i: distances_from_start[i])
 
-        unvisited.remove(current_index)
+            if current_index == target_index:
+                break
 
-        for edge in filter(
-                lambda e: e.start == current_index or e.end == current_index,
-                graph.edges):
-            
-            start = current_index
-            end = edge.end if edge.start == current_index else edge.start
+            unvisited.remove(current_index)
 
-            if end in unvisited and distances_from_start[end] > distances_from_start[start] + edge.length:
-                distances_from_start[end] = distances_from_start[start] + edge.length
-                node_sequences[end] = node_sequences[start].copy()
-                node_sequences[end].append(end)
+            for edge in self.edges_adjacent_to(current_index):
+                start = current_index
+                end = edge.end if edge.start == current_index else edge.start
 
-    return node_sequences[target_index]
+                if end in unvisited and distances_from_start[end] > distances_from_start[start] + edge.length:
+                    distances_from_start[end] = distances_from_start[start] + edge.length
+                    node_sequences[end] = node_sequences[start].copy()
+                    node_sequences[end].append(end)
+
+        return node_sequences[target_index]
 
 
-graph = Graph()
+def main() -> None:
+    graph = Graph()
 
-graph.add_node(1, 2)
-graph.add_node(4, 7)
-graph.add_node(3,1)
-graph.add_node(-2,0)
-graph.add_node(0,0)
+    graph.add_node(1, 2)
+    graph.add_node(4, 7)
+    graph.add_node(3, 1)
+    graph.add_node(-2, 0)
+    graph.add_node(0, 0)
 
-graph.add_edge(0, 1, 1)
-graph.add_edge(1, 2, 2)
-graph.add_edge(2, 3, 3)
-graph.add_edge(3, 0, 1)
-graph.add_edge(1, 3, 3)
+    graph.add_edge(0, 1, 1)
+    graph.add_edge(1, 2, 2)
+    graph.add_edge(2, 3, 3)
+    graph.add_edge(3, 0, 1)
+    graph.add_edge(1, 3, 3)
 
-print(Dijkstra(graph, 0, 5))
\ No newline at end of file
+    print(graph.dijkstra(0, 3))
+
+
+if __name__ == "__main__":
+    main()