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package g1101_1200.s1172_dinner_plate_stacks;

// #Hard #Hash_Table #Stack #Design #Heap_Priority_Queue
// #2022_03_05_Time_63_ms_(96.74%)_Space_121.6_MB_(92.39%)

import java.util.ArrayList;
import java.util.List;
import java.util.Stack;
import java.util.TreeSet;

/**
 * 1172 - Dinner Plate Stacks\.
 *
 * Hard
 *
 * You have an infinite number of stacks arranged in a row and numbered (left to right) from `0`, each of the stacks has the same maximum capacity.
 *
 * Implement the `DinnerPlates` class:
 *
 * *   `DinnerPlates(int capacity)` Initializes the object with the maximum capacity of the stacks `capacity`.
 * *   `void push(int val)` Pushes the given integer `val` into the leftmost stack with a size less than `capacity`.
 * *   `int pop()` Returns the value at the top of the rightmost non-empty stack and removes it from that stack, and returns `-1` if all the stacks are empty.
 * *   `int popAtStack(int index)` Returns the value at the top of the stack with the given index `index` and removes it from that stack or returns `-1` if the stack with that given index is empty.
 *
 * **Example 1:**
 *
 * **Input** 
 *
 * ["DinnerPlates", "push", "push", "push", "push", "push", "popAtStack", "push", "push", "popAtStack", "popAtStack", "pop", "pop", "pop", "pop", "pop"] 
 *
 * [[2], [1], [2], [3], [4], [5], [0], [20], [21], [0], [2], [], [], [], [], []]
 *
 * **Output:** [null, null, null, null, null, null, 2, null, null, 20, 21, 5, 4, 3, 1, -1]
 *
 * **Explanation:** 
 *
 *     DinnerPlates D = DinnerPlates(2); // Initialize with capacity = 2
 *     D.push(1); 
 *     D.push(2); 
 *     D.push(3); 
 *     D.push(4); 
 *     D.push(5);          // The stacks are now: 2 4 
 *                                               1 3 5 
 *                                               ﹈ ﹈ ﹈ 
 *     D.popAtStack(0);    // Returns 2. The stacks are now:   4 
 *                                                        1 3 5 
 *                                                       ﹈ ﹈ ﹈ 
 *     D.push(20);         // The stacks are now: 20 4 
 *                                                 1 3 5 
 *                                                ﹈ ﹈ ﹈ 
 *     D.push(21);         // The stacks are now: 20 4 21 
 *                                                 1 3 5 
 *                                                 ﹈ ﹈ ﹈ 
 *     D.popAtStack(0);    // Returns 20. The stacks are now: 4 21 
 *                                                            1 3 5 
 *                                                           ﹈ ﹈ ﹈ 
 *     D.popAtStack(2);    // Returns 21. The stacks are now: 4 
 *                                                          1 3 5 
 *                                                         ﹈ ﹈ ﹈ 
 *     D.pop()             // Returns 5. The stacks are now: 4 
 *                                                          1 3 
 *                                                          ﹈ ﹈ 
 *     D.pop()             // Returns 4. The stacks are now: 1 3 
 *                                                          ﹈ ﹈ 
 *     D.pop()             // Returns 3. The stacks are now: 1 
 *                                                           ﹈ 
 *     D.pop()             // Returns 1. There are no stacks. 
 *     D.pop()             // Returns -1. There are still no stacks.
 *
 * **Constraints:**
 *
 * *   1 <= capacity <= 2 * 10⁴
 * *   1 <= val <= 2 * 10⁴
 * *   0 <= index <= 10⁵
 * *   At most 2 * 10⁵ calls will be made to `push`, `pop`, and `popAtStack`.
**/
public class DinnerPlates {
    private final List> stacks;
    private int stackCap;
    private TreeSet leftIndex;

    public DinnerPlates(int capacity) {
        stacks = new ArrayList<>();
        stackCap = capacity;
        leftIndex = new TreeSet<>();
    }

    public void push(int val) {
        if (!leftIndex.isEmpty()) {
            int i = leftIndex.first();
            stacks.get(i).push(val);
            if (stacks.get(i).size() == stackCap) {
                leftIndex.remove(i);
            }
            return;
        }
        if (stacks.isEmpty() || stacks.get(stacks.size() - 1).size() == stackCap) {
            Stack newStack = new Stack<>();
            stacks.add(newStack);
        }
        stacks.get(stacks.size() - 1).push(val);
    }

    public int pop() {
        if (stacks.isEmpty()) {
            return -1;
        }
        while (stacks.get(stacks.size() - 1).isEmpty()) {
            leftIndex.remove(stacks.size() - 1);
            stacks.remove(stacks.size() - 1);
        }
        int val = stacks.get(stacks.size() - 1).pop();
        if (stacks.get(stacks.size() - 1).isEmpty()) {
            leftIndex.remove(stacks.size() - 1);
            stacks.remove(stacks.size() - 1);
        }
        return val;
    }

    public int popAtStack(int index) {
        if (stacks.size() - 1 >= index) {
            int val = -1;
            if (!stacks.get(index).isEmpty()) {
                val = stacks.get(index).pop();
            }
            if (stacks.get(index).isEmpty() && index == stacks.size() - 1) {
                leftIndex.remove(stacks.size() - 1);
                stacks.remove(index);
                return val;
            }
            leftIndex.add(index);
            return val;
        }
        return -1;
    }
}