lower_triangle.cpp

该压缩包包含下三角表格采用抽象数据类型实现的头文件和实现文件。

#include"Lower_triangle.h"
#include<iomanip.h>
Lower_triangle::Lower_triangle(int s)
{
	if (s > max_side) s = max_side;
	if (s < 0) s = 0;
	side = s;
	set_access(s);
}
void Lower_triangle::set_access(int s)
{
	for (int i = 0; i < s; i++)
	access[i] = (i * i + i) / 2;
}
int Lower_triangle::get(int i, int j)
{
	if (j > i) {
		int temp = j;
		j = i;
		i = temp;
	}
	if (i >= side || j < 0) return 0;
	return entry[access[i] + j];
}
void Lower_triangle::put(int i, int j, int value)
{
	if (j > i) {
		int temp = j;
		j = i;
		i = temp;
	}
	if (i >= side || j < 0) return;
	entry[access[i] + j] = value;
}
void Lower_triangle::print()
/*
Post: display a lower triangular table
*/

{
	int i, j;
	for (i = 0; i < side; i++) {
		for (j = 0; j <= i; j++)
			cout << get(i,j) <<" ";
				for (j = i + 1; j < side; j++)
					cout <<" 0 "; 
					cout << endl;
	}
}
void Lower_triangle::read()
/*
Post: the entries of a lower triangular table are read
from standard input
*/
{
	int i, j;
	do {
		cout << "How may rows? " << flush;
		cin >> side;
		set_access(side);
	} while (side > max_side || side < 0);
	for (i = 0; i < side; i++) {
		cout << "\nEnter row " << i << " :" << flush;
		for (j = 0; j <= i; j++) {
			int value;
			cin >> value;
			put(i, j, value);
		}
	}
}
bool Lower_triangle::test()
/*
Post: tests the triangle rule
*/
{
	bool okay = true;
	int a, b, c;
	int ab, ac, bc;
	a = 0;
	while (okay && a < side) {
		c = 0;
		while (okay && c <= a) {
			b = 0;
			ac = get(a, c);
			while (okay && b < side) { // test with intermediate cities
				ab = get(a, b);
				bc = get(b, c);
				okay = (ac <= ab + bc); // test triangle rule
				b++;
			}
			c++;
		}
		a++;
	}
	if (okay) {
		cout << "The triangle inequality holds." << endl;
		return true;
	}
	cout<< "The Triangle inequality fails for entries "
		<< a - 1 << " " << c - 1 << " with intermediate location "
		<< b - 1 << endl;
	return false;
}