设计一个哈弗曼编码和译码系统, 要求如下:
B——建树:读入字符集和各字符频度,建立哈夫曼树。
T——遍历:先序和中序遍历二叉树。
E——生成编码:根据已建成的哈夫曼树,产生各个字符的哈夫曼编码。
C——编码:输入由字符集中字符组成的任意字符串,利用已生成的哈夫曼编码进行编码,显示编码结果,并将输入的字符串及其编码结果分别保存在磁盘文件textfile.txt和codefile.txt中。
D——译码:读入codefile.txt,利用已建成的哈夫曼树进行译码,并将译码结果存入磁盘文件result.txt。
P——打印:屏幕显示文件textfile.txt,codefile.txt,result.txt。
X——退出。
提示: 修改教材中二叉树结点类BTNode, 增加一个指向双亲的parent域, 修改二叉树类的函数MakeTree设置该域的值. 通过遍历哈夫曼树, 产生每个叶
子结点的哈夫曼编码. 当遍历访问某个叶节点时, 从该叶结点到根的路径可以确定该叶结点所代表的字符的编码.
忘记初始化debug了一晚上, 顺便复习文件操作. 代码用到了优先队列类以及二叉树类.
实现代码:
#include "iostream" #include "cstdio" #include "cstring" #include "algorithm" #include "cassert" #include "fstream" using namespace std; template <class T> class PrioQueue { public: PrioQueue(int mSize = 0); ~PrioQueue() { delete []q; } bool IsEmpty() const { return n == 0; } // 优先队列为空返回true bool IsFull() const { return n == maxSize; } // 优先队列为满返回true void Append(const T& x); // 优先队列中添加值为x的元素 void Serve(T& x); // 优先队列中弹出队列中优先权最高的元素, 并赋值给x private: void AdjustDown(int r, int j); // 向下调整 void AdjustUp(int j); // 向上调整 void Print(); T* q; int n, maxSize; /* data */ }; template <class T> void PrioQueue<T>::Print() { for(int i = 0; i < n; ++i) cout << q[i] << "\t"; cout << endl; } template <class T> PrioQueue<T>::PrioQueue(int mSize) { maxSize = mSize; n = 0; q = new T[maxSize]; } template <class T> void PrioQueue<T>::AdjustUp(int j) { int i = j; T tmp = q[i]; while(i > 0 && tmp < q[(i - 1) / 2]) { q[i] = q[(i - 1) / 2]; i = (i - 1) / 2; } q[i] = tmp; } template <class T> void PrioQueue<T>::Append(const T& x) { assert(!IsFull()); q[n++] = x; AdjustUp(n - 1); } template <class T> void PrioQueue<T>::Serve(T& x) { x = q[0]; q[0] = q[--n]; AdjustDown(0, n - 1); } template <class T> void PrioQueue<T>::AdjustDown(int r, int j) { int child = 2 * r + 1; T tmp = q[r]; while(child <= j) { if(child < j && q[child] > q[child + 1]) child++; if(tmp <= q[child]) break; q[(child - 1) / 2] = q[child]; child = 2 * child + 1; } q[(child - 1) / 2] = tmp; } template <class T> struct BTNode { /* data */ BTNode() { lChild = rChild = NULL; } BTNode(const T &x, const char &y) { element = x; ch = y; lChild = rChild = parent = NULL; memset(z, -1, sizeof(z)); } BTNode(const T& x, const char &y, BTNode<T>* l, BTNode<T>* r) { element = x; ch = y; lChild = l; rChild = r; parent = NULL; memset(z, -1, sizeof(z)); } T element; BTNode<T>* lChild, *rChild, *parent; char ch; int val, z[100]; }; template <class T> class BinaryTree { public: BinaryTree() { root = NULL; i = -1; } bool IsEmpty() const; // 判断是否为空, 是返回true void Clear(); // 移去所有结点, 成为空二叉树 bool Root(T& x) const; // 若二叉树为空, 则x为根的值, 返回true BTNode<T>* Root(); int Size(); int Count() { return Count(root); } void MakeTree(const T& x, const char &y, BinaryTree<T>& left, BinaryTree<T>& right); // 构造一颗二叉树, 根的值为x, left & right为左右子树 void BreakTree(T& x, BinaryTree<T>& left, BinaryTree<T>& right); // 拆分二叉树为三部分, x为根的值, left & right为左右子树 void PreOrder(void (*Visit)(T& x)); // 先序遍历二叉树 void InOrder(void (*Visit)(T& x)); // 中序遍历二叉树 void PostOrder(void (*Visit)(T& x)); // 后序遍历二叉树 void Create_code(); // 生成编码 void Create_code_out(); // 输出编码 void Code(); // 编码 void Compile(); // 译码 void Print(); BTNode<T>* root; /* data */ private: int i; void Clear(BTNode<T>* t); int Size(BTNode<T> *t); // 返回二叉树结点个数 int Count(BTNode<T> *t); // 返回二叉树只有一个孩子的结点个数 void PreOrder(void (*Visit)(T &x), BTNode<T> *t); void InOrder(void (*Visit)(T &x), BTNode<T> *t); void PostOrder(void (*Visit)(T &x), BTNode<T> *t); void Create_code(BTNode<T> *t); void Create_code_out(BTNode<T> *t); void Code(BTNode<T> *t); void Compile(BTNode<T> *t); void Make(BTNode<T> *t, char a); }; template <class T> void Visit(T &x) { cout << x << '\t'; } template <class T> BTNode<T>* BinaryTree<T>::Root() { return root; } template <class T> bool BinaryTree<T>::Root(T &x) const { if(root) { x = root -> element; return true; } return false; } template <class T> void BinaryTree<T>::Clear(BTNode<T>* t) { if(t) { Clear(t -> lChild); Clear(t -> rChild); cout << "delete" << t -> element << "..." << endl; delete t; } } template <class T> void BinaryTree<T>::MakeTree(const T& x, const char &y, BinaryTree<T> &left, BinaryTree<T> &right) { if(root || &left == &right) return; root = new BTNode<T>(x, y, left.root, right.root); if(left.root != right.root) { left.root -> parent = root; right.root -> parent = root; left.root -> val = 0; right.root -> val = 1; } left.root = right.root = NULL; } template <class T> void BinaryTree<T>::BreakTree(T& x, BinaryTree<T>& left, BinaryTree<T>& right) { if(!root || &left == &right || left.root || right.root) return; x = root -> element; left.root = root -> lChild; right.root = root -> rChild; delete root; root = NULL; } template <class T> void BinaryTree<T>::PreOrder(void (*Visit)(T& x)) { cout << "先序遍历为:" << endl; PreOrder(Visit, root); cout << endl; } template <class T> void BinaryTree<T>::PreOrder(void (*Visit)(T& x), BTNode<T>* t) { if(t) { Visit(t -> element); PreOrder(Visit, t -> lChild); PreOrder(Visit, t -> rChild); } } template <class T> void BinaryTree<T>::InOrder(void (*Visit)(T& x)) { cout << "中序遍历为:" << endl; InOrder(Visit, root); cout << endl; } template <class T> void BinaryTree<T>::InOrder(void (*Visit)(T& x), BTNode<T>* t) { if(t) { InOrder(Visit, t -> lChild); Visit(t -> element); InOrder(Visit, t -> rChild); } } template <class T> void BinaryTree<T>::PostOrder(void (*Visit)(T& x)) { cout << "后序遍历为:" << endl; PostOrder(Visit, root); cout << endl; } template <class T> void BinaryTree<T>::PostOrder(void (*Visit)(T& x), BTNode<T>* t) { if(t) { PostOrder(Visit, t -> lChild); PostOrder(Visit, t -> rChild); Visit(t -> element); } } template <class T> int BinaryTree<T>::Size() { return Size(root); } template <class T> int BinaryTree<T>::Size(BTNode<T> *t) { if(!t) return 0; return Size(t -> lChild) + Size(t -> rChild) + 1; } template <class T> int BinaryTree<T>::Count(BTNode<T> *t) { if(!t) return 0; if(((t -> lChild) && (!t -> rChild)) || ((!t -> lChild) && (t -> rChild))) return 1; return Count(t -> lChild) + Count(t -> rChild); } template <class T> class HfmTree: public BinaryTree<T> { public: operator T() const{ return weight; } T getW() { return weight; } void putW(const T &x) { weight = x; } void SetNull() { BinaryTree<T>::root = NULL; } private: T weight; }; template <class T> HfmTree<T> CreatHfmTree(T w[], char q[], int n) { PrioQueue<HfmTree<T> > pq(n); HfmTree<T> x, y, z, zero; for(int i = 0; i < n; ++i) { z.MakeTree(w[i], q[i], x, y); z.putW(w[i]); pq.Append(z); z.SetNull(); } for(int i = 1; i < n; ++i) { pq.Serve(x); pq.Serve(y); z.MakeTree(x.getW() + y.getW(), 'e', x, y); z.putW(x.getW() + y.getW()); pq.Append(z); z.SetNull(); } pq.Serve(z); return z; } HfmTree<int> HfmT; int num; void Make_HfmT() { char s[100]; int w[100]; cout << "请输入字符个数:" << endl; cin >> num; cout << "请输入权值:" << endl; for(int i = 0; i < num; ++i) cin >> w[i]; cout << "请输入相应字符集:" << endl; cin >> s; HfmT = CreatHfmTree(w, s, num); } void Traversal_HfmT() { HfmT.PreOrder(Visit); HfmT.InOrder(Visit); HfmT.PostOrder(Visit); } template <class T> void BinaryTree<T>::Create_code() { Create_code(root); } template <class T> void BinaryTree<T>::Create_code(BTNode<T> *t) { if(t) { if(t -> parent) { for(int j = 0; j <= i; ++j) t -> z[j] = t -> parent -> z[j]; // 复制双亲编码域 i++; t -> z[i] = t -> val; // 编码中加入自己编码 } Create_code(t -> lChild); Create_code(t -> rChild); i--; } } template <class T> void BinaryTree<T>::Create_code_out() { Create_code_out(root); } template <class T> void BinaryTree<T>::Create_code_out(BTNode<T> *t) { if(t) { if(t -> lChild == t -> rChild) { cout << t -> ch << ':'; int i = 0; while(t -> z[i] != -1) { cout << t -> z[i]; i++; } cout << endl; } Create_code_out(t -> lChild); Create_code_out(t -> rChild); } } template <class T> void BinaryTree<T>::Code() { Code(root); } template <class T> void BinaryTree<T>::Code(BTNode<T> *t) { ofstream outt("textfile.txt"); if(!outt) { cout << "Open textfile.txt failed." << endl; return ; } ofstream outc("codefile.txt", ios::trunc); if(!outc) { cout << "Open codefile.txt failed." << endl; return ; } outc.close(); char s[100]; cout << "请输入由字符集组成的任意字符串:" << endl; cin >> s; outt << s; outt.close(); int len = strlen(s); cout << "编码为:" << endl; for(int i = 0; i < len; ++i) Make(root, s[i]); cout << endl; } template <class T> void BinaryTree<T>::Make(BTNode<T> *t, char a) { int i = 0; if(t) { if(t -> ch == a) { ofstream outc("codefile.txt", ios::app); while(t -> z[i] != -1) { cout << t -> z[i]; outc << t -> z[i]; i++; } outc.close(); return ; } Make(t -> lChild, a); Make(t -> rChild, a); } } template <class T> void BinaryTree<T>::Compile() { Compile(root); } template<class T> void BinaryTree<T>::Compile(BTNode<T> *t) { ifstream inf("codefile.txt"); if(!inf) { cout << "Open codefile.txt failed." << endl; return; } ofstream outs("result.txt",ios::trunc); if(!outs) { cout << "Open result.txt failed." << endl; return; } outs.close(); char *re; char tmp; int n = 0; while(inf.get(tmp) != '\0') n++; inf.close(); re = new char[n+1]; int n2 = 0; ifstream in("codefile.txt"); if(!in) { cout<<"Open codefile.txt failed." << endl; return; } while(in.get(tmp) != '\0') re[n2++] = tmp; BTNode<T> *c; cout << "译码为 :"; int n3 = 0; while(n3 < n) { while(t) { c = t; if(re[n3] == '0') // 左0右1根据0或1向左走向右走直到叶子结点 t = t -> lChild; else t = t -> rChild; n3++; } ofstream outs("result.txt", ios::app); if(!outs) { cout << "Open result.txt failed." << endl; return; } cout << c -> ch; outs << c -> ch; outs.close(); t = root; n3--; } cout << endl; } void Print() { char ch; ifstream a("textfile.txt"); ifstream b("codefile.txt"); ifstream c("result.txt"); if(!a) { cout << "Open textfile.txt failed." << endl; return ; } if(!b) { cout << "Open codefile.txt failed." << endl; return ; } if(!c) { cout << "Open result.txt failed." << endl; return ; } cout << "textfile.txt内容为:" << endl; while(a.get(ch) != '\0') cout << ch; cout << endl; cout << "codefile.txt内容为:" << endl; while(b.get(ch) != '\0') cout << ch; cout << endl; cout << "result.txt内容为:" << endl; while(c.get(ch) != '\0') cout << ch; cout << endl; a.close(); b.close(); c.close(); } void Menu() { cout << "欢迎使用哈夫曼编码和译码系统" << endl; cout << "****************************" << endl; cout << "************菜单************" << endl; cout << "***********B-建树***********" << endl; cout << "***********T-遍历***********" << endl; cout << "*********E-生成编码*********" << endl; cout << "***********C-编码***********" << endl; cout << "***********D-译码***********" << endl; cout << "***********P-打印***********" << endl; cout << "***********X-退出***********" << endl; cout << "****************************" << endl; } int main(int argc, char const *argv[]) { char ch; Menu(); while(cin >> ch && ch != 'X') { switch(ch) { case 'B': { Make_HfmT(); HfmT.Create_code(); break; } case 'T': { Traversal_HfmT(); break; } case 'E': { cout << "编码为:" << endl; HfmT.Create_code_out(); break; } case 'C': { HfmT.Code(); break; } case 'D': { HfmT.Compile(); break; } case 'P': { Print(); break; } default: { cout << "输入有误, 请重新输入." << endl; break; } } Menu(); } return 0; }
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时间: 2024-10-28 23:55:59