多数元素

 public int MajorityElement(int[] nums) {
        Dictionary<int, int> dic = new Dictionary<int ,int>();
            foreach (int num in nums)
            {
                 if(!dic.ContainsKey(num))
                {
                    dic.Add(num, 0);
                }   
                dic[num]++;
            }
            int m = 0;
            int n = nums.Length;
            foreach(KeyValuePair<int,int> k in dic)
            {
                if(k.Value>n/2)
                {
                    m = k.Key;
                }
            }

            return m;     

    }

   public int MajorityElement(int[] nums) {
     Array.Sort(nums);
     return nums[nums.Length/2];
    }