c++使用优先队列来构建huffman树[哈夫曼树]

#include <iostream>
#include <queue>
#include <string.h>
#include <vector>
#include <algorithm>
using namespace std;

char Table[26];

struct Node
{
	int 	freq;
	char 	val;
	Node	* left;
	Node 	* right;
	Node():left(NULL), right(NULL) , freq(0) , val('0'){}
};

class Cmp
{
public:
	bool operator() (const Node * a, const Node * b) const
	{
		return	a->freq > b->freq;  // 从小到大 ，freq 小的 优先级别高 
	}
};

priority_queue<Node* , vector<Node*> , Cmp> myQueue;

void BuildTree()
{
	for (int i = 0; i < 26; ++ i)
	{
		if (Table[i] > 0)
		{
			Node * node = new Node();
			node->freq = Table[i];
			node->val =(char) (i + 'A');
			myQueue.push(node);
		}
	}
	
	while (myQueue.size() > 1)
	{
		Node * f = myQueue.top();
		myQueue.pop();
		Node * s = myQueue.top();
		myQueue.pop();
		Node * tmp = new Node();
		tmp->freq = f->freq + s->freq;
		tmp->left = f;
		tmp->right = s;
		myQueue.push(tmp);
	}
	//cout << myQueue.top()->freq<<endl;
}

struct PrintNode
{
	int freq; 
	char val;
	string code;
};

vector<PrintNode> vpn;
bool cmp(const PrintNode & a , const PrintNode & b)
{
	return a.freq > b.freq;
}

void Print( Node * node , string res)
{
	if (node == NULL)
	{
		return;
	}
	if (node->val != '0')
	{
		PrintNode pn;
		pn.val = node->val;
		pn.freq = node->freq;
		pn.code = res;
		vpn.push_back(pn);
		//cout <<node->val <<" | " << node->freq <<" | "<< res <<endl;
		return ;
	}
	Print(node->left , res + "0");
	Print(node->right, res + "1");
	delete node->left;
	delete node->right;
}

int main()
{
	int N;
	memset(Table , 0 , sizeof(Table));
	cin >> N;
	for (int i = 0; i < N; ++i)
	{
		char ch ;
		cin >> ch;
		if (ch >= 'A' && ch <= 'Z')
		{
			++Table[ch - 'A'];
		}
	}
	BuildTree();
	Node * root = myQueue.top();
	myQueue.pop();
	Print(root , "");
	
	sort(vpn.begin() , vpn.end() , cmp);
	
	for (int i = 0; i < vpn.size(); ++i)
	{
		cout <<vpn[i].val << " "<<vpn[i].freq <<" " << vpn[i].code<<endl;
	}
	return 0;
}

具体的构成算法不再这里讨论了，