LTOJ: Word Ladder II: In progress

There are memory leak, I will use shared_ptr to solve the issue.
LTOJ: Word Ladder II: I think it is a good answer though it could not pass the build in OJ (The shared_ptr is used).
LTOJ: Word Ladder II: Memory Limit Exceeded
LTOJ: Word Ladder II: Solve the Memory Limit Exceeded issue but still meet the TLE
LTOJ: Word Ladder II: Meet Memory Limit Exceeded issue again.
LTOJ: Word Ladder II: In progress