哈夫曼编码

哈夫曼编码的首要思想就是，每次选出两个权重最小的结点，组成一颗新的二叉树，跟结点为两个结点的权重之和，左右孩子为刚选出来的两个结点。然后把这科树放回去，重新选择，直到剩下一颗树。

using namespace std;

typedef struct TNode {
    char value;
    int fre;
    struct TNode* leftNode;
    struct TNode* rightNode;
}TNode;

struct cmp//比较函数，用于优先队列构造最小堆
{
    bool operator() (TNode *node1,TNode *node2)
    {
        return node1->fre>node2->fre; 
    }
};

int calWeight(TNode* root, int deep);
void del(TNode* root);

int main(void)
{

    int n,fre;
    char value;
    while (cin>>n) {
        priority_queuevector, cmp> queue;
        for (int i = 0; i < n; ++i) {
            cin >> value >> fre;
            TNode* node = new TNode;
            node->value = value;
            node->fre = fre;
            node->leftNode = NULL;
            node->rightNode = NULL;
            queue.push(node);
        }
        while (queue.size()>1) {
            struct TNode* node1 = queue.top();
            queue.pop();
            struct TNode* node2 = queue.top();
            queue.pop();
            struct TNode* newNode = new TNode;
            newNode->fre = node1->fre + node2->fre;
            newNode->leftNode = node1;
            newNode->rightNode = node2;
            queue.push(newNode);
        }
        if (queue.size() == 1) {
            struct TNode* root = queue.top();
            queue.pop();
            int result = calWeight(root, 0);
            cout << result << endl;
            del(root);
        }
        else {
            cout << 0 << endl;
        }

    }
    return 0;
}

//递归计算权重 B(T)=∑f(c)dT(c) 叶子节点权重乘以路径长度，累积
int calWeight(TNode* root, int deep) {
    if (NULL == root) 
        return 0;
    if ((NULL == root->leftNode) && (NULL == root->rightNode)) {
        return deep * (root->fre);
    }
    int leftWieght = calWeight(root->leftNode,deep+1);
    int rightWieght = calWeight(root->rightNode, deep + 1);
    return leftWieght + rightWieght;
}

void del(TNode* root) {
    if (NULL == root)
        return;
    del(root->leftNode);
    del(root->rightNode);
    delete(root);
}    

图片出处：
http://www.myexception.cn/program/1829340.html