treehist.cpp

来自「常用算法与数据结构原代码」· C++ 代码 · 共 66 行

// histogramming using a binary search tree

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

class eType 
{
	friend void main(void);
	friend void Add1(eType&);
	friend ostream& operator <<(ostream&, eType);
public:
	operator int() const 
	{
		return key;
	}
private:
	int key,    // element value
		count;  // frequency
};

ostream& operator<<(ostream& out, eType x)
{
	out << x.key << " " << x.count << "   "; 
	return out;
}

void Add1(eType& e) 
{
	e.count++;
}

void main(void)
{// Histogram using a search tree.
	BSTree<eType,int> T;
	int n;  // number of elements
	cout << "Enter number of elements" << endl;
	cin >> n;
	
	// input elements and enter into tree
	for (int i = 1; i <= n; i++) 
	{
		eType e;  // input element
		cout << "Enter element " << i << endl;
		cin >> e.key;
		e.count = 1;
		// put e in tree unless match already there
		// in latter case increase count by 1
		try 
		{
			T.InsertVisit(e, Add1);
		}
		catch (NoMem)
		{
			cout << "Out of memory" << endl;
			exit(1);
		}
	}
	
	// output distinct elements and their counts
	cout << "Distinct elements and frequencies are"
        << endl;
	T.Ascend();
}