# Leetcode - Design a Stack With Increment Operation Solution

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.

## Solution in Python

```
class CustomStack:
def __init__(self, maxSize: int):
self.maxSize = maxSize
self.stack = []
def push(self, x: int) -> None:
if len(self.stack)!=self.maxSize:
self.stack.append(x)
def pop(self) -> int:
if self.stack:
return self.stack.pop()
else:
return -1
def increment(self, k: int, val: int) -> None:
for i in range(min(k,len(self.stack))):
self.stack[i] += val
# Your CustomStack object will be instantiated and called as such:
# obj = CustomStack(maxSize)
# obj.push(x)
# param_2 = obj.pop()
# obj.increment(k,val)
```