2248.Intersection.cs

// 2248. Intersection of Multiple Arrays
// Given a 2D integer array nums where nums[i] is a non-empty array of distinct positive integers, return the list of integers that are present in each array of nums sorted in ascending order.

// Example 1:
// Input: nums = [[3,1,2,4,5],[1,2,3,4],[3,4,5,6]]
// Output: [3,4]
// Explanation: 
// The only integers present in each of nums[0] = [3,1,2,4,5], nums[1] = [1,2,3,4], and nums[2] = [3,4,5,6] are 3 and 4, so we return [3,4].
// Example 2:
// Input: nums = [[1,2,3],[4,5,6]]
// Output: []
// 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.

public class Solution {
    public IList<int> Intersection(int[][] nums) {
        HashSet<int> set = new HashSet<int>(nums[0]);

        for(int  i = 1; i < nums.Length; i++){
            HashSet<int> tempSet = new();
            for(int j =0; j < nums[i].Length; j++){
                if(set.Contains(nums[i][j]))
                    tempSet.Add(nums[i][j]);
            }
            set = tempSet;
        }
        var result = set.ToList();
        result.Sort();
        return result;
    }
}