lower.h

来自「常用算法与数据结构原代码」· C头文件 代码 · 共 61 行

// file lower.h
#ifndef Lower_
#define Lower_

// lower triangle matrix

#include <stdlib.h>
#include <iostream.h>
#include "xcept.h"

template<class T>
class LowerMatrix {
   public:
	   LowerMatrix(int size = 10)
	   {
		   n = size; 
		   t = new T [n*(n+1)/2];
	   }
	   ~LowerMatrix() 
	   {
		   delete [] t;
	   }
	   LowerMatrix<T>& Store(const T& x, int i, int j);
	   T Retrieve(int i, int j) const;
   private:
	   int n; //  matrix dimension
	   T *t;  // 1D array for lower triangle
};

template<class T>
LowerMatrix<T>& LowerMatrix<T>::Store(const T& x, int i, int j)
{// Store x as L(i,j).
	if ( i < 1 || j < 1 || i > n || j > n)
		throw OutOfBounds();
	
	
	// (i,j) in lower triangle iff i >= j
	if (i >= j) 
		t[i*(i-1)/2+j-1] = x;
	else 
		if (x != 0) 
			throw MustBeZero();
	
	return *this;
}

template <class T>
T LowerMatrix<T>::Retrieve(int i, int j) const
{// Retrieve L(i,j).
	if ( i < 1 || j < 1 || i > n || j > n)
		throw OutOfBounds();
	
	// (i,j) in lower triangle iff i >= j
	if (i >= j) 
		return t[i*(i-1)/2+j-1];
	else 
		return 0;
}

#endif