I submitted the same solution twice for the problem https://leetcode.com/problems/serialize-and-deserialize-binary-tree/. \nThe results are as below:\nSubmission 1: Runtime - 39 ms, Memory - 65.7 MB\t\nSubmission 2: Runtime - 13 ms, Memory - 42 MB\t\n\nBoth submissions had exact same code in the same language (java).\n\nCan someone from https://leetcode.com/ explain this?

I submitted the same solution twice for the problem https://leetcode.com/problems/serialize-and-deserialize-binary-tree/. \nThe results are as below:\nSubmissio