Design a Stack With Increment Operation

Design a Stack With Increment Operation is a Medium Data Structures and Algorithms interview problem you can solve, run and submit on Thita.ai. It belongs to the Design Patterns pattern, in the Design (General/Specific) subpattern.

Problem statement

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.

Constraints:

- 1 <= maxSize, x, k <= 1000

- 0 <= val <= 100

- At most 1000 calls will be made to each method of increment, push and pop each separately.

Topics and companies

Topics: Array, Stack, Design.

Reported in interviews at Amazon.

How to practise Design a Stack With Increment Operation on Thita.ai

Starter code is provided in C, C#, C++, Go, Java, JavaScript and Python. Your solution runs against 5 test cases for this problem, with the AI coach available for a hint when you are stuck rather than a finished answer. The reference solution runs in O(1) per push, pop, and increment operation. All operations are constant time due to the use of a lazy increment array. time and O(N), where N is maxSize. We use two arrays of size maxSize: one for the stack and one for the lazy increment values. space.

Open Design a Stack With Increment Operation in the code editor, or read the Design a Stack With Increment Operation editorial for a worked solution with its approach and complexity analysis.

Where Design a Stack With Increment Operation sits in the DSA pattern sheet

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