这周的数据结构实验作业，刚好被抽到号要上交，于是乎在宿舍写了一晚上。
若有错漏之处请斧正！
关于建树的参考博文：http://blog.csdn.net/xgf415/article/details/52628073
实验要求如下：
编译器：VS 2015
运行环境： WIN 10
代码如下：
hfmTree.h
1 #include <string>
2 #include "MinHeap.h"
3 #include <stack>
4 #include <sstream>
5 using namespace std;
6 #pragma once
7
8
9 const char EndTag = ‘#‘; //读写文件标识用，用来标记NULL孩子指针
10 const char NoneTag = ‘*‘; //建树识别用，非字符结点
11 class HuffmanTree; //前置声明
12 class Node
13 {
14 private:
15 char ch;
16 float wei;
17 string code;
18 Node *lc, *rc;
19
20 friend class HuffmanTree;
21 public :
22 Node() : ch(NoneTag),wei(0),code(),lc(NULL),rc(NULL){}
23 Node(char c, float w) {
24 ch = c;
25 wei= w;
26 lc = NULL;
27 rc = NULL;
28 }
29
30 float getWeight() { return wei; }
31 char getChar() { return ch; }
32 string getCode() { return code; }
33 Node* getRightChild() const { return rc; }
34 Node* getLeftChild() const { return lc; }
35 void setCodes(const string &s) { code = s; }
36 void set(const Node& l, const Node & r) { lc = new Node(l); rc = new Node(r); }
37 void clone(Node &n) {
38 ch = n.getChar();
39 wei = n.getWeight();
40 code = n.getCode();
41 lc = n.getLeftChild();
42 rc = n.getRightChild();
43 }
44
45 bool hasChild()
46 {
47 return rc != NULL && lc != NULL;
48 }
49
50 Node &operator = (const Node &n) {
51 ch = n.ch;
52 wei = n.wei;
53 code = n.code;
54 lc = n.lc;
55 rc = n.rc;
56 return *this;
57 }
58
59 bool operator <=(Node &R) {
60 return wei <= R.wei;
61 }
62
63 bool operator >(Node &R) {
64 return wei > R.wei;
65 }
66
67 bool operator < (Node &R) {
68 return wei < R.wei;
69 }
70
71 friend ostream & operator << (ostream &out, const Node& n) {
72 out << "Char:" << n.ch << ‘\t‘ << "Weight:" << n.wei << endl;
73 return out;
74 }
75
76 };
77
78 class HuffmanTree
79 {
80 private:
81 int size; //结点数，包括空格结点
82 Node *root;
83 bool has_EndTag;
84
85 float averageLen;
86 public:
87 HuffmanTree() {
88 size = 0;
89 has_EndTag = false;
90 root = NULL;
91 }
92
93 //建立哈夫曼树
94 HuffmanTree(MinHeap<Node> &mh)
95 {
96 has_EndTag = false;
97 Node first, second;
98 while (mh.getSize() != 1)
99 {
100 mh.RemoveMin(first);
101 mh.RemoveMin(second);
102 Node h(NoneTag, first.getWeight() + second.getWeight());
103 h.set(first, second);
104 mh.Insert(h);
105 }
106 mh.RemoveMin(first);
107 root = new Node(first);
108 }
109
110 void BuildTree(MinHeap<Node> &mh)
111 {
112 if (root != NULL) DeleteTree(root);
113 has_EndTag = false;
114 Node first, second;
115 while (mh.getSize() != 1)
116 {
117 mh.RemoveMin(first);
118 mh.RemoveMin(second);
119 Node h(NoneTag, first.getWeight() + second.getWeight());
120 h.set(first, second);
121 mh.Insert(h);
122 }
123 mh.RemoveMin(first);
124 root = new Node(first);
125 }
126
127 void DeleteTree(Node *t) //删除以t为根的子树
128 {
129 if (t == NULL)
130 return;
131 else
132 {
133 Node *p1 = t->lc;
134 Node *p2 = t->rc;
135 if (p1 != NULL) DeleteTree(p1);
136 if (p2 != NULL) DeleteTree(p2);
137 delete t;
138 }
139 }
140 void Initialize()
141 {
142 string s = "";
143 Initialization(root, s);
144 }
145
146 void Initialization(Node *n,string s) //初始化编码表
147 {
148 if (n == NULL) return;
149 n->code = s;
150 Initialization(n->lc, s + ‘0‘);
151 Initialization(n->rc, s + ‘1‘);
152 }
153
154 void addTag(Node *p) //添加结尾标志的递归函数（方便读写文件）
155 {
156 if (p->lc == NULL)
157 {
158 Node *t = new Node(EndTag, 0);
159 p->lc = t;
160 }
161 else addTag(p->lc);
162 if (p->rc == NULL)
163 {
164 Node *t = new Node(EndTag, 0);
165 p->rc = t;
166 }
167 else addTag(p->rc);
168 }
169
170 void addLeafTag() //给Huffman树添加叶子结点的空子女标志结点#，方便文件读写
171 {
172 addTag(root);
173 has_EndTag = true;
174 }
175
176 void delTag(Node *p) //删除叶子结点的空子女标志结点的递归函数
177 {
178 if (p == NULL)
179 return;
180 if (p->ch == EndTag)
181 delete p;
182 if (p->rc != NULL)
183 delTag(p->rc);
184 if (p->lc != NULL)
185 delTag(p->lc);
186 }
187
188 void delLeafTag() //删除叶子结点的空子女标志结点
189 {
190 delTag(root);
191 has_EndTag = false;
192 }
193
194 void SaveTable(ostream &os) //储存编码表到文件(非递归前序遍历)
195 {
196
197 if (!has_EndTag)
198 addLeafTag();
199 stack<Node *> S;
200 Node *p = root;
201 S.push(p);
202 while (!S.empty())
203 {
204 p = S.top(); S.pop();
205 Node temp = *p;
206 os << temp.ch << ‘ ‘ << temp.wei <<‘ ‘ << temp.code << endl;
207 if (p->lc != NULL) S.push(p->lc);
208 if (p->rc != NULL) S.push(p->rc);
209 }
210 }
211
212 void ReadTable(istream &is) //读取编码表
213 {
214 if (root != NULL) DeleteTree(root);
215 ReadTable(is, root);
216 if (root == NULL)
217 cout << "error !读取文件遇到问题！" << endl;
218 }
219
220 void ReadTable(istream &is, Node *&dest) //读取编码表的递归函数
221 {
222 if (!is.eof())
223 {
224 string line;
225 getline(is, line);
226 Node temp;
227 stringstream ss(line);
228 if (line[0] == ‘ ‘)
229 {
230 temp.ch = ‘ ‘;
231 ss >> temp.wei >> temp.code;
232 }
233 else
234 ss >> temp.ch >> temp.wei >> temp.code;
235 if (temp.ch == EndTag)
236 {
237 dest = NULL;
238 return;
239 }
240 dest = new Node(temp);
241 ReadTable(is, dest->lc);
242 ReadTable(is, dest->rc);
243 }
244 }
245
246 void ShowTree()
247 {
248 Show(root);
249 averageLen = averageLen / size;
250 cout << "平均编码长度：" << averageLen << endl;
251 }
252
253 void Show(Node *n) //前序遍历输出编码结果
254 {
255 if (n == NULL) return;
256 if (n->ch != NoneTag)
257 {
258 cout << n->ch << "：";
259 cout <<n->code << endl;
260 averageLen += n->code.length();
261 size++;
262 }
263 Show(n->lc);
264 Show(n->rc);
265 }
266
267 string getCode(char c) //给字符c编码，返回c的编码
268 {
269 Node *p = SearchChar(root,c);
270 if (p == NULL)
271 {
272 cout << "找不到" << c << "对应的编码" << endl;
273 exit(1);
274 }
275 else
276 return p->code;
277 }
278
279 Node *SearchChar(Node *p,char c) //查找字符为c的结点递归函数
280 {
281 if (p->ch == c)
282 return p;
283 else
284 {
285 Node *cur = NULL;
286 if (p->rc != NULL)
287 {
288 Node *rc = SearchChar(p->rc, c);
289 if (rc != NULL) cur = rc;
290 }
291 if (p->lc != NULL)
292 {
293 Node *lc = SearchChar(p->lc, c);
294 if (lc != NULL) cur = lc;
295 }
296 return cur;
297 }
298 }
299
300 char getChar(string c) //解码，返回编码c对应的字符
301 {
302 Node *p = SearchCode(root, c);
303 if (p == NULL) { cout << "解码失败，该字符不存在" << endl; return NoneTag; }
304 else return p->ch;
305 }
306
307 Node *SearchCode(Node *p, string c) //查找编码为c的对应字符结点
308 {
309 if (p->code == c)
310 return p;
311 else
312 {
313 Node *cur = NULL;
314 if (p->rc != NULL)
315 {
316 Node *rc = SearchCode(p->rc, c);
317 if (rc != NULL) cur = rc;
318 }
319 if (p->lc != NULL)
320 {
321 Node *lc = SearchCode(p->lc, c);
322 if (lc != NULL) cur = lc;
323 }
324 return cur;
325 }
326 }
327 };
建树要用到优先级队列，用最小堆模板类实现，代码如下：
MinHeap.h
1 #pragma once
2 #define DefaultSize 10
3 template<class E>
4 class MinHeap
5 {
6 private:
7 E *heap;
8 int currentSize;
9 int maxHeapSize;
10 void siftDown(int start, int m);
11 void siftUp(int start);
12 public:
13 MinHeap(int sz = DefaultSize);
14 MinHeap(E arr[], int n);
15 ~MinHeap() { delete[]heap; }
16 bool Insert(const E &x);
17 bool RemoveMin(E &x);
18 bool IsEmpty()const
19 {return (currentSize == 0) ? true : false;}
20 bool IsFull() const{return (currentSize == maxHeapSize) ? true : false;}
21 void MakeEmpty() { currentSize = 0; }
22
23 int getSize() const { return currentSize; }
24 void showAll() {
25 for (int i = 0; i < currentSize; ++i)
26 cout << heap[i];
27 }
28 };
29
30 template<class E>
31 MinHeap<E>::MinHeap(int sz)
32 {
33 maxHeapSize = (DefaultSize < sz) ? sz : DefaultSize;
34 heap = new E[maxHeapSize];
35 if (heap == NULL) {
36 exit(1);
37 }
38 currentSize = 0;
39 }
40
41 template<class E>
42 MinHeap<E>::MinHeap(E arr[], int n)
43 {
44 maxHeapSize = (DefaultSize < n) ? n : DefaultSize;
45 heap = new E[maxHeapSize];
46 if (heap == NULL) {
47 exit(1);
48 }
49 for (int i = 0; i < n; ++i) heap[i] = arr[i];
50 currentSize = n;
51 int currentPos = (currentSize - 2) / 2;
52 while (currentPos >= 0)
53 {
54 siftDown(currentPos, currentSize - 1);
55 currentPos--;
56 }
57 }
58
59 template<class E>
60 void MinHeap<E>::siftDown(int start, int m)
61 {
62 if(m <= start) return;
63 int i = start, j = 2 * i + 1;
64 E temp = heap[i];
65 while (j <= m)
66 {
67 if (j < m && heap[j] > heap[j + 1]) j++;
68 if (temp <= heap[j]) break;
69 else { heap[i] = heap[j]; i = j; j = 2 * j + 1; }
70 }
71 heap[i] = temp;
72 }
73
74 template<class E>
75 void MinHeap<E>::siftUp(int start)
76 {
77 int j = start, i = (j - 1) / 2; // i : parent, j : current
78 E temp = heap[j];
79 while (j > 0)
80 {
81 if (heap[i] <= temp) break; // parent is smaller
82 else {
83 heap[j] = heap[i];
84 j = i;
85 i = (i - 1) / 2;
86 }
87 }
88 heap[j] = temp;
89 }
90
91 template<class E>
92 bool MinHeap<E>::Insert(const E& x)
93 {
94 if (currentSize == maxHeapSize)
95 {
96 exit(1);
97 }
98 heap[currentSize] = x;
99 siftUp(currentSize);
100 currentSize++;
101 return true;
102 }
103
104 template<class E>
105 bool MinHeap<E>::RemoveMin(E &x)
106 {
107 if (currentSize == 0) {
108 std::cout << "Heap empty!" << std::endl;
109 std::cout << currentSize << endl;
110 return false;
111 }
112 else
113 {
114 x = heap[0];
115 heap[0] = heap[currentSize - 1];
116 currentSize--;
117 siftDown(0, currentSize - 1);
118 return true;
119 }
120
121 }
下面是main.cpp
1 #include <iostream>
2 #include <fstream>
3 #include "hfmTree.h"
4 #define MaxCh 50
5 using namespace std;
6 const char * TreeFile = "hfmTree.txt";
7 const char * ToBeTran = "ToBeTran.txt";
8 const char * CodeFile = "CodeFile.txt";
9 const char * TextFile = "TextFile.txt";
10
11 void showMenu()
12 {
13 cout << "\t\tI：初始化（Initialization）" << endl;
14 cout << "\t\tE：编码（Encoding）" << endl;
15 cout << "\t\tD：译码（Decoding）" << endl;
16 cout << "\t\tW: 重新写入正文" << endl;
17 cout << "\t\tQ：退出" << endl;
18 cout << endl;
19 }
20
21 void eatLine()
22 {
23 string line;
24 getline(cin,line);
25 }
26
27 HuffmanTree hfmTree;
28 bool has_init = false;
29 void Initialization()
30 {
31 MinHeap<Node> mh(MaxCh);
32 int n;
33 cout << "请输入字符集中字符个数：";
34 cin >> n;
35 eatLine();
36 while (n--)
37 {
38 char ch;
39 float wei;
40 cout << "输入编码字符：";
41 ch = getchar();
42 eatLine();
43 cout << "输入权值：";
44 cin >> wei;
45 eatLine();
46 Node t(ch, wei);
47 mh.Insert(t);
48 cout << t;
49 }
50 hfmTree.BuildTree(mh);
51 hfmTree.Initialize();
52 cout << "初始化编码表结果：" << endl;
53 hfmTree.ShowTree();
54 ofstream fout(TreeFile);
55 hfmTree.SaveTable(fout);
56 cout << "写入文件成功！" << endl;
57 has_init = true;
58 fout.close();
59 }
60
61 void ReadTreeFile()
62 {
63 ifstream fin(TreeFile, ios::app);
64 hfmTree.ReadTable(fin);
65 hfmTree.ShowTree();
66 fin.close();
67 has_init = true;
68 }
69
70 void WriteText()
71 {
72 ofstream fout(ToBeTran);
73 if (!fout.is_open())
74 {
75 cout << "打开文件" << ToBeTran << "失败" << endl;
76 return;
77 }
78 string text;
79 eatLine();
80 cout << "请输入需要编码的文本：" << endl;
81 getline(cin, text);
82 fout << text;
83 cout << "写入原始文本成功！" << endl;
84 fout.close();
85 }
86
87 void Encoding()
88 {
89 if (has_init == false)
90 ReadTreeFile();
91
92 ifstream fin(ToBeTran);
93 if (!fin.is_open())
94 {
95 cout << "打开文件" << ToBeTran << "失败" << endl;
96 return;
97 }
98
99 string text;
100 getline(fin, text);
101 cout << "将要给下述文本编码:" << endl;
102 cout << text << endl;
103
104 int len = text.length();
105 cout << "length:" << len << endl;
106
107 string code;
108 for (int i = 0; i < len; ++i)
109 {
110 string c = hfmTree.getCode(text[i]);
111 code += c;
112 }
113 cout << "编码结果为：" << endl;
114 cout << code << endl;
115 ofstream fout(CodeFile);
116 if (!fout.is_open())
117 {
118 cout << "打开文件" << CodeFile << "失败" << endl;
119 return;
120 }
121 fout << code;
122 cout << "编码成功！" << endl;
123 fout.close();
124 fin.close();
125 }
126
127 void Decoding()
128 {
129 if (has_init == false)
130 ReadTreeFile();
131 ifstream fin(CodeFile);
132 if (!fin.is_open())
133 {
134 cout << "打开文件" << ToBeTran << "失败" << endl;
135 return;
136 }
137 string code;
138 fin >> code;
139 cout << "将要给下述编码进行解码:" << endl;
140 cout << code << endl;
141 string text;
142 int len = code.length();
143 string codenow;
144 for (int i = 0; i < len; ++i)
145 {
146 codenow += code[i];
147 char temp = hfmTree.getChar(codenow);
148 if (temp != NoneTag) { text += temp; codenow.clear(); }
149 }
150 cout << "解码结果为：" << endl;
151 cout << text <<endl;
152 ofstream fout(TextFile);
153 fout << text;
154
155 fin.close();
156 fout.close();
157 }
158
159 int main()
160 {
161 cout << "请输入字符进行下述操作：" << endl << endl;
162 while (1)
163 {
164 char tag;
165 showMenu();
166 cin >> tag;
167 switch (tag)
168 {
169 case ‘I‘:
170 Initialization();
171 break;
172 case ‘E‘:
173 Encoding();
174 break;
175 case ‘D‘:
176 Decoding();
177 break;
178 case ‘Q‘:
179 return 0;
180 case ‘W‘:
181 WriteText();
182 break;
183 default:
184 cout << "请输入正确的字符!" << endl;
185 cin >> tag;
186 break;
187 }
188 }
189
190 return 0;
191 }
时间： 2024-10-12 01:59:11