for aWord in words:
vertices.add(aWord)
for i in range(len(aWord)):
newWord = aWord[0:i] + "*" + aWord[i + 1:]
if newWord not in specialDict:
specialDict[newWord] = [aWord]
else:
for aConnection in specialDict[newWord]:
edges.add((aWord, aConnection))
specialDict[newWord].append(aWord)
# Construct the graph
graph = Graph(vertices, edges)
# Find word ladders
while True:
source = input("Source word: ")
if source not in vertices:
print("Unknown word:", source, "\n")
continue
target = input("Target word: ")
if target not in vertices:
print("Unknown word:", target, "\n")
continue
parents = graph.bfs(source)
ladder = Graph.path(target, parents)
print("Shortest ladder:", ladder, "\n")
