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g2201_2300.s2241_design_an_atm_machine.readme.md Maven / Gradle / Ivy

2241\. Design an ATM Machine

Medium

There is an ATM machine that stores banknotes of `5` denominations: `20`, `50`, `100`, `200`, and `500` dollars. Initially the ATM is empty. The user can use the machine to deposit or withdraw any amount of money.

When withdrawing, the machine prioritizes using banknotes of **larger** values.

*   For example, if you want to withdraw `$300` and there are `2` `$50` banknotes, `1` `$100` banknote, and `1` `$200` banknote, then the machine will use the `$100` and `$200` banknotes.
*   However, if you try to withdraw `$600` and there are `3` `$200` banknotes and `1` `$500` banknote, then the withdraw request will be rejected because the machine will first try to use the `$500` banknote and then be unable to use banknotes to complete the remaining `$100`. Note that the machine is **not** allowed to use the `$200` banknotes instead of the `$500` banknote.

Implement the ATM class:

*   `ATM()` Initializes the ATM object.
*   `void deposit(int[] banknotesCount)` Deposits new banknotes in the order `$20`, `$50`, `$100`, `$200`, and `$500`.
*   `int[] withdraw(int amount)` Returns an array of length `5` of the number of banknotes that will be handed to the user in the order `$20`, `$50`, `$100`, `$200`, and `$500`, and update the number of banknotes in the ATM after withdrawing. Returns `[-1]` if it is not possible (do **not** withdraw any banknotes in this case).

**Example 1:**

**Input**

["ATM", "deposit", "withdraw", "deposit", "withdraw", "withdraw"]

[[], [[0,0,1,2,1]], [600], [[0,1,0,1,1]], [600], [550]]

**Output:** [null, null, [0,0,1,0,1], null, [-1], [0,1,0,0,1]]

**Explanation:**

    ATM atm = new ATM();
    atm.deposit([0,0,1,2,1]); // Deposits 1 $100 banknote, 2 $200 banknotes,
                              // and 1 $500 banknote.
    atm.withdraw(600);        // Returns [0,0,1,0,1]. The machine uses 1 $100 banknote
                              // and 1 $500 banknote. The banknotes left over in the
                              // machine are [0,0,0,2,0].
    atm.deposit([0,1,0,1,1]); // Deposits 1 $50, $200, and $500 banknote.
                              // The banknotes in the machine are now [0,1,0,3,1].
    atm.withdraw(600);        // Returns [-1]. The machine will try to use a $500 banknote
                              // and then be unable to complete the remaining $100,
                              // so the withdraw request will be rejected.
                              // Since the request is rejected, the number of banknotes
                              // in the machine is not modified.
    atm.withdraw(550);        // Returns [0,1,0,0,1]. The machine uses 1 $50 banknote
                              // and 1 $500 banknote.

**Constraints:**

*   `banknotesCount.length == 5`
*   0 <= banknotesCount[i] <= 109
*   1 <= amount <= 109
*   At most `5000` calls **in total** will be made to `withdraw` and `deposit`.
*   At least **one** call will be made to each function `withdraw` and `deposit`.