1381 - Design a Stack With Increment Operation\.

Medium

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.