_1381.java

package com.fishercoder.solutions;

import java.util.ArrayList;
import java.util.List;

/**
 * 1381. Design a Stack With Increment Operation
 *
 * 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.
 * */
public class _1381 {
    public static class Solution1 {
        public static class CustomStack {

            List<Integer> list;
            int maxSize;

            public CustomStack(int maxSize) {
                this.list = new ArrayList<>();
                this.maxSize = maxSize;
            }

            public void push(int x) {
                if (list.size() >= maxSize) {
                    return;
                } else {
                    list.add(x);
                }
            }

            public int pop() {
                if (!list.isEmpty()) {
                    return list.remove(list.size() - 1);
                } else {
                    return -1;
                }
            }

            public void increment(int k, int val) {
                for (int i = 0; i < k && i < list.size(); i++) {
                    list.set(i, list.get(i) + val);
                }
            }
        }
    }
}