1 #include <iostream> 2 #include <vector> 3 #include <algorithm> 4 using namespace std; 5 6 //Huffman树的节点类 7 typedef struct Node 8 { 9 char value; //结点的字符值 10 int weight; //结点字符出现的频度 11 Node *lchild, *rchild; //结点的左右孩子 12 }Node; 13 14 //自定义排序规则，即以vector中node结点weight值升序排序 15 bool ComNode(Node *p, Node *q) 16 { 17 return p->weight<q->weight; 18 } 19 20 //构造Huffman树，返回根结点指针 21 Node* BuildHuffmanTree(vector<Node*> vctNode) 22 { 23 while (vctNode.size()>1) //vctNode森林中树个数大于1时循环进行合并 24 { 25 sort(vctNode.begin(), vctNode.end(), ComNode); //依频度高低对森林中的树进行升序排序 26 27 Node *first = vctNode[0]; //取排完序后vctNode森林中频度最小的树根 28 Node *second = vctNode[1]; //取排完序后vctNode森林中频度第二小的树根 29 Node *merge = new Node; //合并上面两个树 30 merge->weight = first->weight + second->weight; 31 merge->lchild = first; 32 merge->rchild = second; 33 34 vector<Node*>::iterator iter; 35 iter = vctNode.erase(vctNode.begin(), vctNode.begin() + 2); //从vctNode森林中删除上诉频度最小的两个节点first和second 36 vctNode.push_back(merge); //向vctNode森林中添加合并后的merge树 37 } 38 return vctNode[0]; //返回构造好的根节点 39 } 40 41 //用回溯法来打印编码 42 void PrintHuffman(Node *node, vector<int> vctchar) 43 { 44 if (node->lchild == NULL && node->rchild == NULL) 45 {//若走到叶子节点，则迭代打印vctchar中存的编码 46 cout << node->value << ": "; 47 for (vector<int>::iterator iter = vctchar.begin(); iter != vctchar.end(); iter++) 48 cout << *iter; 49 cout << endl; 50 return; 51 } 52 else 53 { 54 vctchar.push_back(1); //遇到左子树时给vctchar中加一个1 55 PrintHuffman(node->lchild, vctchar); 56 vctchar.pop_back(); //回溯，删除刚刚加进去的1 57 vctchar.push_back(0); //遇到左子树时给vctchar中加一个0 58 PrintHuffman(node->rchild, vctchar); 59 vctchar.pop_back(); //回溯，删除刚刚加进去的0 60 61 } 62 } 63 64 int main() 65 { 66 cout << "************ Huffman编码问题 ***************" << endl; 67 cout << "请输入要编码的字符,并以空格隔开（个数任意）：" << endl; 68 vector<Node*> vctNode; //存放Node结点的vector容器vctNode 69 char ch; //临时存放控制台输入的字符 70 while ((ch = getchar()) != ' ') 71 { 72 if (ch == ' ')continue; //遇到空格时跳过，即没输入一个字符空一格空格 73 Node *temp = new Node; 74 temp->value = ch; 75 temp->lchild = temp->rchild = NULL; 76 vctNode.push_back(temp); //将新的节点插入到容器vctNode中 77 } 78 79 cout << endl << "请输入每个字符对应的频度，并以空格隔开：" << endl; 80 for (int i = 0; i<vctNode.size(); i++) 81 cin >> vctNode[i]->weight; 82 83 Node *root = BuildHuffmanTree(vctNode); //构造Huffman树，将返回的树根赋给root 84 vector<int> vctchar; 85 cout << endl << "对应的Huffman编码如下：" << endl; 86 PrintHuffman(root, vctchar); 87 88 system("pause"); 89 }