1381.DesignaStackWithIncrementOperation.py

"""
    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:

    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.
"""
#Difficulty: Medium
#34 / 34 test cases passed.
#Runtime: 140 ms
#Memory Usage: 14.2 MB

#Runtime: 140 ms, faster than 58.90% of Python3 online submissions for Design a Stack With Increment Operation.
#Memory Usage: 14.2 MB, less than 100.00% of Python3 online submissions for Design a Stack With Increment Operation.

class CustomStack:

    def __init__(self, maxSize: int):
        self.stack = []
        self.index = 0
        self.size = maxSize

    def push(self, x: int) -> None:
        if self.index < self.size:
            self.stack.append(x)
            self.index = min(self.index + 1, self.size)

    def pop(self) -> int:
        if self.stack:
            self.index -= 1
            return self.stack.pop()
        return -1

    def increment(self, k: int, val: int) -> None:
        k = min(k, self.index)
        for i in range(k):
            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)