关于组合数计算的算法我写了好几个，发现杨辉三角查表法效率比较高！
并且这个算法利用C(n,k) = C(n,n-k)来简化杨辉三角的数组，算法的时间复杂度比较低。
原创，水平有限，如有不足，欢迎指出。
Mail：rainday163@163.com
下面是我写的代码并附带测试函数：Dev-C++ 4.9.9.2下测试通过。
/*---------------------------------------------------------------------
//file name:combination.cpp
//Coder: rainday163
//E-mail: rainday1631@163.com
//Create date: 2009.9.4
//Last modify date: 2009.9.28
//Test platform: WinXP sp2 & Dev-C++ 4.9.9.2
---------------------------------------------------------------------*/
#include <typeinfo>
#include <vector>
#include <stdexcept>
#include <iostream>
template <typename T1,typename T2>
T1 combination(T2 const &n,T2 const &k)
{
//类型检查
if( !( (typeid(T1) == typeid(unsigned long long))
||(typeid(T1) == typeid(long long))
||(typeid(T1) == typeid(unsigned long))
||(typeid(T1) == typeid(long))
||(typeid(T1) == typeid(unsigned int))
||(typeid(T1) == typeid(int))
||(typeid(T1) == typeid(unsigned short))
||(typeid(T1) == typeid(short)) ) )
{
throw std::out_of_range("Type of return value Error!");
}
if( !( (typeid(T2) == typeid(long))
|| (typeid(T2) == typeid(unsigned int))
|| (typeid(T2) == typeid(int))
|| (typeid(T2) == typeid(unsigned short))
|| (typeid(T2) == typeid(short))
) )
{
throw std::out_of_range("Type of parameter Error!");
}
if((n|k)<0)//确保n,k为正值
{
throw std::out_of_range("Error：negative parameter!");
}
if(n<k)
{
throw std::out_of_range("Error：K > N ,Please check your input!");
&nb
C/C++
头文件一览
//////////////////////////////////////////////////////////////////////////
C
头文件
(C89,C95)
(C++98,C++03也包含)
include <assert.h> //诊断库
include <ctype.h> //字符处理函数库
include <errno.h> //错误定义
include <float.h& ......
