Explanation: There does not exist any integer present both in nums[0] and nums[1], so we return an empty list [].

Constraints

1 <= nums.length <= 1000
1 <= sum(nums[i].length) <= 1000
1 <= nums[i][j] <= 1000
All the values of nums[i] are unique.

Solution

Method 1 – Hash Map Counting

Intuition

We want to find elements that appear in every array. By counting the occurrences of each number across all arrays, we can select those that appear in all of them.

Approach

Use a hash map to count the number of arrays each integer appears in.
For each array, add 1 to the count for each unique integer.
After processing all arrays, collect integers whose count equals the number of arrays.
Sort the result in ascending order.

Code

[{"language":"C++","code":"vector<int> intersection(vector<vector<int>>& nums) {\n    unordered_map<int, int> cnt;\n    int n = nums.size();\n    for (auto& arr : nums) {\n        for (int x : arr) cnt[x] = 0;\n    }\n    for (auto&

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