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package g2301_2400.s2349_design_a_number_container_system;

// #Medium #Hash_Table #Design #Heap_Priority_Queue #Ordered_Set
// #2022_07_30_Time_208_ms_(54.57%)_Space_166.7_MB_(43.08%)

import java.util.HashMap;
import java.util.Map;
import java.util.TreeSet;

/**
 * 2349 - Design a Number Container System\.
 *
 * Medium
 *
 * Design a number container system that can do the following:
 *
 * *   **Insert** or **Replace** a number at the given index in the system.
 * *   **Return** the smallest index for the given number in the system.
 *
 * Implement the `NumberContainers` class:
 *
 * *   `NumberContainers()` Initializes the number container system.
 * *   `void change(int index, int number)` Fills the container at `index` with the `number`. If there is already a number at that `index`, replace it.
 * *   `int find(int number)` Returns the smallest index for the given `number`, or `-1` if there is no index that is filled by `number` in the system.
 *
 * **Example 1:**
 *
 * **Input**
 *
 * ["NumberContainers", "find", "change", "change", "change", "change", "find", "change", "find"]
 *
 * [ [], [10], [2, 10], [1, 10], [3, 10], [5, 10], [10], [1, 20], [10]]
 *
 * **Output:** [null, -1, null, null, null, null, 1, null, 2]
 *
 * **Explanation:**
 *
 *     NumberContainers nc = new NumberContainers();
 *     nc.find(10); // There is no index that is filled with number 10. Therefore, we return -1.
 *     nc.change(2, 10); // Your container at index 2 will be filled with number 10.
 *     nc.change(1, 10); // Your container at index 1 will be filled with number 10.
 *     nc.change(3, 10); // Your container at index 3 will be filled with number 10.
 *     nc.change(5, 10); // Your container at index 5 will be filled with number 10.
 *     nc.find(10); // Number 10 is at the indices 1, 2, 3, and 5. Since the smallest index that is filled with 10 is 1, we return 1.
 *     nc.change(1, 20); // Your container at index 1 will be filled with number 20. Note that index 1 was filled with 10 and then replaced with 20.
 *     nc.find(10); // Number 10 is at the indices 2, 3, and 5. The smallest index that is filled with 10 is 2. Therefore, we return 2. 
 *
 * **Constraints:**
 *
 * *   1 <= index, number <= 10⁹
 * *   At most 10⁵ calls will be made **in total** to `change` and `find`.
**/
@SuppressWarnings("java:S1186")
public class NumberContainers {
    private Map> indices = new HashMap<>();
    private Map vals = new HashMap<>();

    public NumberContainers() {}

    public void change(int index, int number) {
        if (vals.containsKey(index)) {
            int old = vals.get(index);
            indices.get(old).remove(index);
            if (indices.get(old).isEmpty()) {
                indices.remove(old);
            }
        }
        vals.put(index, number);
        indices.computeIfAbsent(number, s -> new TreeSet<>()).add(index);
    }

    public int find(int number) {
        if (indices.containsKey(number)) {
            return indices.get(number).first();
        }
        return -1;
    }
}

/*
 * Your NumberContainers object will be instantiated and called as such:
 * NumberContainers obj = new NumberContainers();
 * obj.change(index,number);
 * int param_2 = obj.find(number);
 */