#region 字符串排列
/// <summary>
/// 输入字符串，打印该字符串的所有排列
/// </summary>
class ListOperator<T> where T:IComparable<T>
{
private List<T> str;
public ListOperator()
{
if (str == null)
str = new List<T>();
}
public ListOperator(List<T> list)
{
if (str == null)
str = new List<T>();
str = list;
}
/// <summary>
/// 排列
/// </summary>
/// <param name="m"></param>
public void Permutation()
{
Console.WriteLine();
if (str == null || str.Count == 0)
return;
Permutation(str,0);
Console.WriteLine();
}
public void Permutation(List<T> pStr,int begin)
{
if (begin == str.Count)
{
pStr.ForEach(l => Console.Write(l));
Console.Write(" , ");
}
else
{
for (int pCh = begin; pCh != pStr.Count; pCh++)
{
T temp = pStr[pCh];
pStr[pCh] = pStr[begin];
pStr[begin] = temp;
Permutation(pStr, begin + 1);
temp = pStr[pCh];
pStr[pCh] = pStr[begin];
pStr[begin] = temp;
}
}
}
/// <summary>
/// 组合
/// </summary>
/// <param name="m"></param>
public void Combine(int m)
{
if (str.Count < m)
return;
List<T> result =new List<T>();
Combine(str,ref result,m);
}
public void Combine(List<T> pStr,ref List<T> result, int m)
{
if (m == 0)
{
result.ForEach(r => Console.Write(r));
Console.Write(",");
//result.Add(default(T));
}
else
{
if (pStr.Count == 0)
return;
result.Add(pStr[0]);
Combine(pStr.GetRange(1, pStr.Count - 1), ref result, m - 1);
result.RemoveAt(result.Count - 1);
Combine(pStr.GetRange(1, pStr.Count - 1), ref result, m);
}
}
/// <summary>
/// 数组中出现次数超过一半的数字
/// </summary>
/// <param name="m"></param>
#region 方法一，此方法修改了数组
public T MoreThanHalfByPartion()
{
if (str == null || str.Count == 0)
return default(T);
int middle = str.Count >> 1;
int start = 0;
int end = str.Count - 1;
int index = Partition(str, start, end);
while (index != middle)
{
if (index < middle)
{
start = index + 1;
index = Partition(str, start, end);
}
else
{
end = index - 1;
index = Partition(str, start,end );
}
}
if (!CheckMoreThanHalf(str[index]))
Console.WriteLine(str[index] + "的结果并没有超过一半！");
return str[index];
}
public int Partition(List<T> num,int start,int end)
{
T pivotkey = num[start];
while (start < end)
{
while (num[end].CompareTo(pivotkey)>=0 && start < end)
end--;
T temp = num[start];
num[start] = num[end];
num[end] = temp;
while (num[start].CompareTo(pivotkey) <= 0 && start < end)
start++;
temp = num[start];
num[start] = num[end];
num[end] = temp;
}
return start;
}
#endregion
#region 方法二，此方法没有修改了数组
public T MoreThanHalfByFeature()
{
if(str==null || str.Count==0)
return default(T);
T result = default(T);
int times = 0;
str.ForEach(
delegate (T num)
{
if (times == 0)
{
result = num;
times = 1;
}
else if (num.CompareTo(result) == 0)
{
times++;
}
else
times--;
}
);
if (!CheckMoreThanHalf(result))
Console.WriteLine(result+"的结果并没有超过一半！");
return result;
}
public bool CheckMoreThanHalf(T result)
{
int times = 0;
str.ForEach(
delegate(T num)
{
if (num.CompareTo(result) == 0)
times++;
});
if (times * 2 <= str.Count)
return false;
return true;
}
#endregion
#region 丑数问题
/// <summary>
/// 我们把只包含因子2、3、5的数称作丑数(ugly number)。求按从小到大的第1500个丑数。例如
/// 6,8是丑数，14不是，因为它包含因子7.习惯是我们把1作为第一个丑数。
/// </summary>
public int GetUglyNumber(int index)
{
System.DateTime startTime = System.DateTime.Now;
if(index<=0)
return 0;
List<int> pUglyNumber = new List<int>() { 1 };
int pMultiply2 = 0;
int pMultiply3 = 0;
int pMultiply5 = 0;
int nextUglyIndex =1;
while (nextUglyIndex < index)
{
int min = Min(pUglyNumber[pMultiply2]*2,pUglyNumber[pMultiply3]*3,pUglyNumber[pMultiply5]*5);
pUglyNumber.Add(min);
while (pUglyNumber[pMultiply2] * 2 <= pUglyNumber[nextUglyIndex])
pMultiply2++;
while (pUglyNumber[pMultiply3] * 3 <= pUglyNumber[nextUglyIndex])
pMultiply3++;
while (pUglyNumber[pMultiply5] * 5 <= pUglyNumber[nextUglyIndex])
pMultiply5++;
nextUglyIndex++;
}
System.DateTime endTime = System.DateTime.Now;
TimeSpan span = endTime.Subtract(startTime);
Console.WriteLine("计算时间："+span.TotalMilliseconds);
return pUglyNumber.Last();
}
public int Min(int number1, int number2, int number3)
{
int min = number1 < number2 ? number1 : number2;
min = number3 < min ? number3 : min;
return min;
}
#endregion
void Check()
{
try
{
if (str == null)
throw new Exception("str不存在！");
else if (str.Count == 0)
throw new Exception("str没有元素！");
else
throw new Exception("未知错误！");
}
catch(Exception ex)
{
Console.WriteLine(ex.Message);
}
}
}
#endregion
