# GeetCode Hub

You have an infinite number of stacks arranged in a row and numbered (left to right) from 0, each of the stacks has the same maximum `capacity`.

Implement the `DinnerPlates` class:

• `DinnerPlates(int capacity)` Initializes the object with the maximum `capacity` of the stacks.
• `void push(int val)` Pushes the given positive integer `val` into the leftmost stack with size less than `capacity`.
• `int pop()` Returns the value at the top of the rightmost non-empty stack and removes it from that stack, and returns `-1` if all stacks are empty.
• `int popAtStack(int index)` Returns the value at the top of the stack with the given `index` and removes it from that stack, and returns -1 if the stack with that given `index` is empty.

Example:

```Input:
["DinnerPlates","push","push","push","push","push","popAtStack","push","push","popAtStack","popAtStack","pop","pop","pop","pop","pop"]
[[2],[1],[2],[3],[4],[5],[0],[20],[21],[0],[2],[],[],[],[],[]]
Output:
[null,null,null,null,null,null,2,null,null,20,21,5,4,3,1,-1]

Explanation:
DinnerPlates D = DinnerPlates(2);  // Initialize with capacity = 2
D.push(1);
D.push(2);
D.push(3);
D.push(4);
D.push(5);         // The stacks are now:  2  4
1  3  5
﹈ ﹈ ﹈
D.popAtStack(0);   // Returns 2.  The stacks are now:     4
1  3  5
﹈ ﹈ ﹈
D.push(20);        // The stacks are now: 20  4
1  3  5
﹈ ﹈ ﹈
D.push(21);        // The stacks are now: 20  4 21
1  3  5
﹈ ﹈ ﹈
D.popAtStack(0);   // Returns 20.  The stacks are now:     4 21
1  3  5
﹈ ﹈ ﹈
D.popAtStack(2);   // Returns 21.  The stacks are now:     4
1  3  5
﹈ ﹈ ﹈
D.pop()            // Returns 5.  The stacks are now:      4
1  3
﹈ ﹈
D.pop()            // Returns 4.  The stacks are now:   1  3
﹈ ﹈
D.pop()            // Returns 3.  The stacks are now:   1
﹈
D.pop()            // Returns 1.  There are no stacks.
D.pop()            // Returns -1.  There are still no stacks.
```

Constraints:

• `1 <= capacity <= 20000`
• `1 <= val <= 20000`
• `0 <= index <= 100000`
• At most `200000` calls will be made to `push`, `pop`, and `popAtStack`.

class DinnerPlates { public DinnerPlates(int capacity) { } public void push(int val) { } public int pop() { } public int popAtStack(int index) { } } /** * Your DinnerPlates object will be instantiated and called as such: * DinnerPlates obj = new DinnerPlates(capacity); * obj.push(val); * int param_2 = obj.pop(); * int param_3 = obj.popAtStack(index); */