# You are given two 2D integer arrays, items1 and items2, representing two sets 
# of items. Each array items has the following properties: 
# 
#  
#  items[i] = [valuei, weighti] where valuei represents the value and weighti 
# represents the weight of the iᵗʰ item. 
#  The value of each item in items is unique. 
#  
# 
#  Return a 2D integer array ret where ret[i] = [valuei, weighti], with weighti 
# being the sum of weights of all items with value valuei. 
# 
#  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 <= valuei, weighti <= 1000 
#  Each valuei in items1 is unique. 
#  Each valuei in items2 is unique. 
#  
# 
#  Related Topics Array Hash Table Sorting Ordered Set 👍 223 👎 9


# leetcode submit region begin(Prohibit modification and deletion)
from collections import defaultdict


class Solution:
    def mergeSimilarItems(self, items1: List[List[int]], items2: List[List[int]]) -> List[List[int]]:
        ret = []
        cnt = defaultdict(int)
        for val, weight in items1:
            cnt[val] += weight
        for val, weight in items2:
            cnt[val] += weight
        for key in range(1, 1001):
            if key in cnt:
                ret.append([key, cnt[key]])
        return ret

# leetcode submit region end(Prohibit modification and deletion)
