[转]组合算法（从几个数字中选几个然后组合）

最新推荐文章于 2022-10-12 11:38:09 发布

转载最新推荐文章于 2022-10-12 11:38:09 发布 · 1.5k 阅读

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CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/penglink/archive/2010/01/21/1653665.html

文章标签：

#c#

本文介绍了一种高效的组合算法实现，并通过实例展示了如何应用于彩票号码的选择。该算法包括三种不同的实现方式：非递归方法、基于字典的递归方法及二进制编码迭代法，每种方法都有其独特之处。

组合算法，很不错，可以拿来选福彩双色球33选6，哈哈！

代码

private void button1_Click(object sender, EventArgs e)
{
int n = 33;
int m = 6;
string[] set = new string[n];
for (int i = 0; i < n; i++)
{
set[i] = (i).ToString().PadLeft(2, '0');
}
List<string> result;

GC.Collect();

result = GetCombinationF2(set, m); //n=20 about 44ms, n=40 about 6s
//result = GetCombinationF3(set, m);//n=20 about 16ms n=40 about 2.5s
//result = GetCombinationF4(set, m);//n=20 about 95ms n=40 about 13s

for (int i = 0; i < 10; i++)
{
this.txtResult.Text += result[i] + "\r\n" ;
}
}

#region 组合算法
#region 组合算法2(非递归方法)
static List<string> GetCombinationF2(string[] strArray, int selectCount)
{
int totalCount = strArray.Length;
int[] currentSelect = new int[selectCount];
int last = selectCount - 1;
List<string> output = new List<string>();
string s;

//付初始值
for (int i = 0; i < selectCount; i++)
currentSelect[i] = i;

while (true)
{
s = "";
//输出部分,生成的时候从0计数,所以输出的时候+1
for (int i = 0; i < selectCount; i++)
{
s += strArray[currentSelect[i]] + "\t";
}
output.Add(s);

//如果不进位
if (currentSelect[last] < totalCount - 1)
currentSelect[last]++;
else
{
//进位部分
int position = last;

while (position > 0 && currentSelect[position - 1] == currentSelect[position] - 1)
position--;

if (position == 0)
break;

currentSelect[position - 1]++;

for (int i = position; i < selectCount; i++)
currentSelect[i] = currentSelect[i - 1] + 1;
}
}
return output;
}
#endregion

#region 组合算法3
static List<string> GetCombinationF3(string[] data, int count)
{
Dictionary<string, int> dic = new Dictionary<string, int>();
List<string> output = new List<string>();
for (int i = 0; i < data.Length; i++)
{
dic.Add(data[i], i);
}
SelectN(dic, data, count, 1, ref output);
return output;
}

static void SelectN(Dictionary<string, int> dd, string[] data, int count, int times, ref List<string> output)
{
//当前字典中的key与原始数据中值大于自身的每个key组合，比如第一轮递归中，01与02-33这些数组合，02与03-33这些数组合。递归五次，即可从33个数中选出6个。
Dictionary<string, int> dic = new Dictionary<string, int>();

foreach (KeyValuePair<string, int> kv in dd)
{
for (int i = kv.Value + 1; i < data.Length; i++)
{
if (times < count - 1)
{
dic.Add(kv.Key + "\t" + data[i], i);
}
else
{
output.Add(kv.Key + "\t" + data[i]);//不考虑输出，将此句注释掉
}
}
}
times++;
if (dic.Count > 0) SelectN(dic, data, count, times, ref output);
}
#endregion

#region 组合算法4
static List<string> GetCombinationF4(string[] data, int count)
{
List<string> output = new List<string>();
int len = data.Length;
string start = "1".PadRight(count, '1').PadRight(len, '0');
string s;
while (start != string.Empty)
{
s = "";
for (int i = 0; i < len; i++)
if (start[i] == '1') s += data[i] + "\t";
output.Add(s);
start = GetNext(start);
}
return output;

}

static string GetNext(string str)
{
string next = string.Empty;
int pos = str.IndexOf("10");
if (pos < 0) return next;
else if (pos == 0) return "01" + str.Substring(2);
else
{
int len = str.Length;
next = str.Substring(0, pos).Replace("0", "").PadRight(pos, '0') + "01";
if (pos < len - 2) next += str.Substring(pos + 2);
}
return next;
}
#endregion
#endregion

转载于:https://www.cnblogs.com/penglink/archive/2010/01/21/1653665.html