[LeetCode] Programming Bug Note

1. Delete Element In Unordered ArrayList, Vectors

    a. Say delete 3 from 1 3 5 7 9, we replace 3 with 9 and erase 9, resulting in 1 9 5 7 9

    b. But when deleting element 9, when we replace 9 with 9, then delete 9, (Seems works ok)

        But in the Leetcode problem Insert 380 381 Delete GetRandom O(1), when the index of the removed element, 1 in example 1, and 4 in example 2 is going to be used again in the future. Index 4 is actually out of bound in the second example.

        In this case, operation sequence matters, it is infact two different types of operation sequence, while the result coincidents in some cases.