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349. Intersection of Two Arrays

Given two arrays, write a function to compute their intersection.

Example:
Given nums1 = [1, 2, 2, 1]nums2 = [2, 2], return [2].

Note:

    • Each element in the result must be unique.
    • The result can be in any order.

解法1:

public int[] Intersection(int[] nums1, int[] nums2) {        var hashtable = new HashSet<int>();        foreach(var n in nums1)        {            hashtable.Add(n);        }        var res = new List<int>();        foreach(var n in nums2 )        {            if(hashtable.Contains(n) && !res.Contains(n))            {                res.Add(n);            }        }        return res.ToArray();    }

 

 

解法2:

public int[] Intersection(int[] nums1, int[] nums2) {        var res = new List<int>();        Array.Sort(nums1);        Array.Sort(nums2);        int size1 = nums1.Count();        int size2 = nums2.Count();        int i = 0;        int j = 0;        int lastNumber =0;        while(i<size1 && j<size2)        {            if(nums1[i] == nums2[j])            {                if(res.Count()==0 || nums1[i] != res[res.Count()-1])                res.Add(nums1[i]);                i++;                j++;            }            else if(nums1[i] < nums2[j])            {                i++;            }            else            {                j++;            }        }        return res.ToArray();    }

 

349. Intersection of Two Arrays