算法基础系列之二：随机数及重复字符统计

//程序一定有些不好、不对的地方，还请大大们一定告诉我

//1.如何按随机顺序输出1到10这10个数，这是我一次面试时人家问的？

static void Main(string[] args)

{

    int[] intArray = new int[10];

    for (int i = 0; i < 10; i++)

    {

        intArray[i] = i + 1;

    }

 

    Random r = new Random();

    for (int i = 9; i >= 0; i--)

    {

        int index = r.Next(i+1);

        Console.WriteLine(intArray[index].ToString());

        if (index != i)

        {

            intArray[index] = intArray[i];

        }

    }

 }

 

 

//2.统计字符串中重复次数最多的字符

//方法一：

static void CountRepeat(string s)

{

    List<char> list = new List<char>();

    list.AddRange(s.ToCharArray());

    list.Sort();

 

    char c = list[0];

    int temp = 1;

    char maxChar = ' ';

    int maxCount = 0;

 

    for (int i = 1; i < list.Count; i++)

    {

        if (list[i] == c)

        {

            temp++;

        }

 

        if (list[i] != c || i == list.Count - 1)

        {

            if (temp > maxCount)

            {

                maxCount = temp;

                maxChar = c;

            }

            temp = 1;

        }

        c = list[i];

    }

    Console.WriteLine(maxChar.ToString() + "  " + maxCount.ToString());

 

}

 

//方法二：

static void CountRepeat(string s)

{

    Dictionary<char, int> dict = new Dictionary<char, int>();

    char maxChar = Char.MinValue;

    int maxCount = 0;

 

    foreach (char c in s)

    {

        if (dict.ContainsKey(c))

        {

            dict[c]++;

        }

        else

        {

            dict.Add(c, 1);

        }

    }

    foreach (KeyValuePair<char, int> kvp in dict)

    {

        if (kvp.Value > maxCount)

        {

            maxCount = kvp.Value;

            maxChar = kvp.Key;

        }

    }

    Console.WriteLine(maxChar.ToString() + "  " + maxCount.ToString());

}