Fix when len is not used

bin/src/graph.dart

@@ -371,7 +371,14 @@ class Graphs {
           var dt = splitted.split(sep.dotToLength);
           if (dt.length == 2) {
             dot.add(int.parse(dt[0]));
+            if (_useLength) {
               len.add(int.parse(dt[1]));
+            } else {
+              len.add(0);
+            }
+          } else if (dt.length == 1) {
+            dot.add(int.parse(splitted));
+            len.add(0);
           }
         }
         _dots.add(Dot.fromTwoLists(name, dot, len));
@@ -503,5 +510,29 @@ class Graphs {
     }
     return label;
   }
+
+  void dijkstra(int source) {
+    /*
+      create vertex set Q;
+
+      for each vertex v in Graph{            
+          dist[v] ← INFINITY ;                
+          prev[v] ← UNDEFINED  ;            
+          add v to Q;}                     
+      dist[source] ← 0;                       
+     
+      while Q is not empty{
+         u ← vertex in Q with min dist[u]   
+                                             
+          remove u from Q
+         
+          for each neighbor v of u still in Q{
+              alt ← dist[u] + length(u, v);
+              if alt < dist[v]:  {            
+                  dist[v] ← alt;
+                  prev[v] ← u;}
+  }}
+      return dist[], prev[]*/
+  }
   //************Алгоритмы************
 }