Package g1301_1400.s1381_design_a_stack_with_increment_operation

Class CustomStack

  • public class CustomStack
extends Object
    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.

    • Constructor Detail

      • CustomStack

        public CustomStack​(int maxSize)

    • Method Detail

      • push

        public void push​(int x)

      • pop

        public int pop()

      • increment

        public void increment​(int k,
                      int val)