Design a Stack With Increment Operation

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Description

Design a stack that supports increment operations on its elements.

Implement the CustomStack class:

- CustomStack(int maxSize) Initializes the object with maxSize which is the maximum number of elements in the stack.

- void push(int x) Adds x to the top of the stack if the stack has not reached the maxSize.

- int pop() Pops and returns the top of the 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, 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 stk = new CustomStack(3); // Stack is Empty []

stk.push(1); // stack becomes [1]

stk.push(2); // stack becomes [1, 2]

stk.pop(); // return 2 --> Return top of the stack 2, stack becomes [1]

stk.push(2); // stack becomes [1, 2]

stk.push(3); // stack becomes [1, 2, 3]

stk.push(4); // stack still [1, 2, 3], Do not add another elements as size is 4

stk.increment(5, 100); // stack becomes [101, 102, 103]

stk.increment(2, 100); // stack becomes [201, 202, 103]

stk.pop(); // return 103 --> Return top of the stack 103, stack becomes [201, 202]

stk.pop(); // return 202 --> Return top of the stack 202, stack becomes [201]

stk.pop(); // return 201 --> Return top of the stack 201, stack becomes []

stk.pop(); // return -1 --> Stack is empty return -1.

Solution