251230

public int solution(int[] array)
    {
        int answer = 0;

        int maxNum = 0;
        int maxNumCount = 0;
        bool doubleFlag = false;

        for (int i = 0; i < array.Length; i++)
        {
            int tempNumCount = 0;

            for (int j = 0; j < array.Length; j++)
                if (array[i] == array[j])
                    tempNumCount++;

            if (tempNumCount > maxNumCount)
            {
                maxNum = array[i];
                maxNumCount = tempNumCount;
                doubleFlag = false;
            }
            else if (tempNumCount == maxNumCount && array[i] != maxNum)
                doubleFlag = true;
        }

        if (doubleFlag)
            answer = -1;
        else
            answer = maxNum;

        return answer;
    }

public int solution(int[] array) {
        Dictionary<int, int> counts = new Dictionary<int, int>();
        foreach (int num in array) {
            if (counts.ContainsKey(num)) {
                counts[num]++;
            } else {
                counts[num] = 1;
            }
        }

        int maxCount = 0;
        int same = -1;
        bool sameCheck = false;

        foreach (var pair in counts) {
            if (pair.Value > maxCount) {
                maxCount = pair.Value;
                same = pair.Key;
                sameCheck = false;
            } else if (pair.Value == maxCount) {
                sameCheck = true;
            }
        }

        if (sameCheck) {
            return -1;
        } else {
            return same;
        }
    }