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# 1381. Design a Stack With Increment Operation

<https://leetcode.com/problems/design-a-stack-with-increment-operation>

## Description

Design a stack which supports the following operations.

Implement the `CustomStack` class:

* `CustomStack(int maxSize)` Initializes the object with `maxSize` which is the maximum number of elements in the stack or do nothing if the stack reached the `maxSize`.
* `void push(int x)` Adds `x` to the top of the stack if the stack hasn't reached the `maxSize`.
* `int pop()` Pops and returns the top of stack or **-1** if the stack is empty.
* `void inc(int k, int val)` Increments the bottom `k` elements of the stack by `val`. If there are less than `k` elements in the stack, just increment all the elements in the stack.

**Example 1:**

```
**Input**
["CustomStack","push","push","pop","push","push","push","increment","increment","pop","pop","pop","pop"]
[[3],[1],[2],[],[2],[3],[4],[5,100],[2,100],[],[],[],[]]
**Output**
[null,null,null,2,null,null,null,null,null,103,202,201,-1]
**Explanation**
CustomStack customStack = new CustomStack(3); // Stack is Empty []
customStack.push(1);                          // stack becomes [1]
customStack.push(2);                          // stack becomes [1, 2]
customStack.pop();                            // return 2 --> Return top of the stack 2, stack becomes [1]
customStack.push(2);                          // stack becomes [1, 2]
customStack.push(3);                          // stack becomes [1, 2, 3]
customStack.push(4);                          // stack still [1, 2, 3], Don't add another elements as size is 4
customStack.increment(5, 100);                // stack becomes [101, 102, 103]
customStack.increment(2, 100);                // stack becomes [201, 202, 103]
customStack.pop();                            // return 103 --> Return top of the stack 103, stack becomes [201, 202]
customStack.pop();                            // return 202 --> Return top of the stack 102, stack becomes [201]
customStack.pop();                            // return 201 --> Return top of the stack 101, stack becomes []
customStack.pop();                            // return -1 --> Stack is empty return -1.
```

**Constraints:**

* `1 <= maxSize <= 1000`
* `1 <= x <= 1000`
* `1 <= k <= 1000`
* `0 <= val <= 100`
* At most `1000` calls will be made to each method of `increment`, `push` and `pop` each separately.

## ac

```java
```