g2301_2400.s2363_merge_similar_items.Solution Maven / Gradle / Ivy

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package g2301_2400.s2363_merge_similar_items;

// #Easy #Array #Hash_Table #Sorting #Ordered_Set
// #2022_08_14_Time_3_ms_(100.00%)_Space_43_MB_(100.00%)

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

/**
 * 2363 - Merge Similar Items\.
 *
 * Easy
 *
 * You are given two 2D integer arrays, `items1` and `items2`, representing two sets of items. Each array `items` has the following properties:
 *
 * *   items[i] = [value_i, weight_i] where value_i represents the **value** and weight_i represents the **weight** of the i^th item.
 * *   The value of each item in `items` is **unique**.
 *
 * Return _a 2D integer array_ `ret` _where_ ret[i] = [value_i, weight_i]_,_ _with_ weight_i _being the **sum of weights** of all items with value_ value_i.
 *
 * **Note:** `ret` should be returned in **ascending** order by value.
 *
 * **Example 1:**
 *
 * **Input:** items1 = \[\[1,1],[4,5],[3,8]], items2 = \[\[3,1],[1,5]]
 *
 * **Output:** [[1,6],[3,9],[4,5]]
 *
 * **Explanation:** 
 * The item with value = 1 occurs in items1 with weight = 1 and in items2 with weight = 5, total weight = 1 + 5 = 6. 
 *
 * The item with value = 3 occurs in items1 with weight = 8 and in items2 with weight = 1, total weight = 8 + 1 = 9. 
 *
 * The item with value = 4 occurs in items1 with weight = 5, total weight = 5. 
 *
 * Therefore, we return [[1,6],[3,9],[4,5]].
 *
 * **Example 2:**
 *
 * **Input:** items1 = \[\[1,1],[3,2],[2,3]], items2 = \[\[2,1],[3,2],[1,3]]
 *
 * **Output:** [[1,4],[2,4],[3,4]]
 *
 * **Explanation:** 
 * The item with value = 1 occurs in items1 with weight = 1 and in items2 with weight = 3, total weight = 1 + 3 = 4. 
 *
 * The item with value = 2 occurs in items1 with weight = 3 and in items2 with weight = 1, total weight = 3 + 1 = 4. 
 *
 * The item with value = 3 occurs in items1 with weight = 2 and in items2 with weight = 2, total weight = 2 + 2 = 4. Therefore, we return [[1,4],[2,4],[3,4]].
 *
 * **Example 3:**
 *
 * **Input:** items1 = \[\[1,3],[2,2]], items2 = \[\[7,1],[2,2],[1,4]]
 *
 * **Output:** [[1,7],[2,4],[7,1]]
 *
 * **Explanation:** 
 *
 * The item with value = 1 occurs in items1 with weight = 3 and in items2 with weight = 4, total weight = 3 + 4 = 7. 
 *
 * The item with value = 2 occurs in items1 with weight = 2 and in items2 with weight = 2, total weight = 2 + 2 = 4. 
 *
 * The item with value = 7 occurs in items2 with weight = 1, total weight = 1. 
 *
 * Therefore, we return [[1,7],[2,4],[7,1]].
 *
 * **Constraints:**
 *
 * *   `1 <= items1.length, items2.length <= 1000`
 * *   `items1[i].length == items2[i].length == 2`
 * *   1 <= value_i, weight_i <= 1000
 * *   Each value_i in `items1` is **unique**.
 * *   Each value_i in `items2` is **unique**.
**/
public class Solution {
    public List> mergeSimilarItems(int[][] arr1, int[][] arr2) {
        int[] cache = new int[1001];
        for (int[] num : arr1) {
            cache[num[0]] += num[1];
        }
        for (int[] num : arr2) {
            cache[num[0]] += num[1];
        }
        List> result = new ArrayList<>();
        for (int i = 0; i < cache.length; i++) {
            int weight = cache[i];
            if (weight > 0) {
                int value = i;
                result.add(Arrays.asList(value, weight));
            }
        }
        return result;
    }
}