You are given an integer `n` and an array of unique integers `blacklist`. Design an algorithm to pick a random integer in the range `[0, n - 1]` that is not in `blacklist`. Any integer that is in the mentioned range and not in `blacklist` should be equally likely to be returned.

Optimize your algorithm such that it minimizes the number of calls to the built-in random function of your language.

Implement the `Solution` class:

- `Solution(int n, int[] blacklist)` Initializes the object with the integer `n` and the blacklisted integers `blacklist`.
- `int pick()` Returns a random integer in the range `[0, n - 1]` and not in `blacklist`.

Example 1:

    Input
    ["Solution", "pick", "pick", "pick", "pick", "pick", "pick", "pick"]
    [[7, [2, 3, 5]], [], [], [], [], [], [], []]
    Output
    [null, 0, 4, 1, 6, 1, 0, 4]

    Explanation
    Solution solution = new Solution(7, [2, 3, 5]);
    solution.pick(); // return 0, any integer from [0,1,4,6] should be ok. Note that for every call of pick,
                     // 0, 1, 4, and 6 must be equally likely to be returned (i.e., with probability 1/4).
    solution.pick(); // return 4
    solution.pick(); // return 1
    solution.pick(); // return 6
    solution.pick(); // return 1
    solution.pick(); // return 0
    solution.pick(); // return 4

Constraints:

- `1 <= n <= 109`
- `0 <= blacklist.length <- min(105, n - 1)`
- `0 <= blacklist[i] < n`
- All the values of `blacklist` are unique.
- At most `2 * 104` calls will be made to `pick`.