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Design Front Middle Back Queue - Practice Coding | SlaveCode

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1670. Design Front Middle Back Queue

Medium

30 Points

Array

Linked List

Design

Queue

Data Stream

Design a queue that supports push and pop operations in the front, middle, and back. Implement the FrontMiddleBack class: Notice that when there are two middle position choices, the operation is performed on the frontmost middle position choice. For example:

Examples

Example 1

Input: ["FrontMiddleBackQueue", "pushFront", "pushBack", "pushMiddle", "pushMiddle", "popFront", "popMiddle", "popMiddle", "popBack", "popFront"] [[], [1], [2], [3], [4], [], [], [], [], []] Output: [null, null, null, null, null, 1, 3, 4, 2, -1] Explanation: FrontMiddleBackQueue q = new FrontMiddleBackQueue(); q.pushFront(1); // [1] q.pushBack(2); // [1, 2] q.pushMiddle(3); // [1, 3, 2] q.pushMiddle(4); // [1, 4, 3, 2] q.popFront(); // return 1 -> [4, 3, 2] q.popMiddle(); // return 3 -> [4, 2] q.popMiddle(); // return 4 -> [2] q.popBack(); // return 2 -> [] q.popFront(); // return -1 -> [] (The queue is empty)

Constraints

1 <= val <= 109
At most 1000 calls will be made to pushFront, pushMiddle, pushBack, popFront, popMiddle, and popBack.

1670. Design Front Middle Back Queue

Medium

30 Points

Array

Linked List

Design

Queue

Data Stream

Design a queue that supports push and pop operations in the front, middle, and back. Implement the FrontMiddleBack class: Notice that when there are two middle position choices, the operation is performed on the frontmost middle position choice. For example:

Examples

Example 1

Input: ["FrontMiddleBackQueue", "pushFront", "pushBack", "pushMiddle", "pushMiddle", "popFront", "popMiddle", "popMiddle", "popBack", "popFront"] [[], [1], [2], [3], [4], [], [], [], [], []] Output: [null, null, null, null, null, 1, 3, 4, 2, -1] Explanation: FrontMiddleBackQueue q = new FrontMiddleBackQueue(); q.pushFront(1); // [1] q.pushBack(2); // [1, 2] q.pushMiddle(3); // [1, 3, 2] q.pushMiddle(4); // [1, 4, 3, 2] q.popFront(); // return 1 -> [4, 3, 2] q.popMiddle(); // return 3 -> [4, 2] q.popMiddle(); // return 4 -> [2] q.popBack(); // return 2 -> [] q.popFront(); // return -1 -> [] (The queue is empty)

Constraints

1 <= val <= 109
At most 1000 calls will be made to pushFront, pushMiddle, pushBack, popFront, popMiddle, and popBack.