基于C++實現的哈夫曼編碼解碼操作示例

2020-05-23 13:30:54

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本文實例講述了基于C++實現的哈夫曼編碼解碼操作。分享給大家供大家參考，具體如下：

哈夫曼編碼是一個通過哈夫曼樹進行的一種編碼，一般情況下，以字符：‘0'與‘1'表示。編碼的實現過程很簡單，只要實現哈夫曼樹，通過遍歷哈夫曼樹，這里我們從每一個葉子結點開始向上遍歷，如果該結點為父節點的左孩子，則在字符串后面追加“0”，如果為其右孩子，則在字符串后追加“1”。結束條件為沒有父節點。然后將字符串倒過來存入結點中。

C++實現代碼如下：

#include<iostream>#include<string>using namespace std;struct Node{  double weight;  string ch;  string code;  int lchild, rchild, parent;};void Select(Node huffTree[], int *a, int *b, int n)//找權值最小的兩個a和b{  int i;  double weight = 0; //找最小的數  for (i = 0; i <n; i++)  {    if (huffTree[i].parent != -1)   //判斷節點是否已經選過      continue;    else    {      if (weight == 0)      {        weight = huffTree[i].weight;        *a = i;      }      else      {        if (huffTree[i].weight < weight)        {          weight = huffTree[i].weight;          *a = i;        }      }    }  }  weight = 0; //找第二小的數  for (i = 0; i < n; i++)  {    if (huffTree[i].parent != -1 || (i == *a))//排除已選過的數      continue;    else    {      if (weight == 0)      {        weight = huffTree[i].weight;        *b = i;      }      else      {        if (huffTree[i].weight < weight)        {          weight = huffTree[i].weight;          *b = i;        }      }    }  }  int temp;  if (huffTree[*a].lchild < huffTree[*b].lchild) //小的數放左邊  {    temp = *a;    *a = *b;    *b = temp;  }}void Huff_Tree(Node huffTree[], int w[], string ch[], int n){  for (int i = 0; i < 2 * n - 1; i++) //初始過程  {    huffTree[i].parent = -1;    huffTree[i].lchild = -1;    huffTree[i].rchild = -1;    huffTree[i].code = "";  }  for (int i = 0; i < n; i++)  {    huffTree[i].weight = w[i];    huffTree[i].ch = ch[i];  }  for (int k = n; k < 2 * n - 1; k++)  {    int i1 = 0;    int i2 = 0;    Select(huffTree, &i1, &i2, k); //將i1，i2節點合成節點k    huffTree[i1].parent = k;    huffTree[i2].parent = k;    huffTree[k].weight = huffTree[i1].weight + huffTree[i2].weight;    huffTree[k].lchild = i1;    huffTree[k].rchild = i2;  }}void Huff_Code(Node huffTree[], int n){  int i, j, k;  string s = "";  for (i = 0; i < n; i++)  {    s = "";    j = i;    while (huffTree[j].parent != -1) //從葉子往上找到根節點    {      k = huffTree[j].parent;      if (j == huffTree[k].lchild) //如果是根的左孩子，則記為0      {        s = s + "0";      }      else      {        s = s + "1";      }      j = huffTree[j].parent;    }    cout << "字符 " << huffTree[i].ch << " 的編碼：";    for (int l = s.size() - 1; l >= 0; l--)    {      cout << s[l];      huffTree[i].code += s[l]; //保存編碼    }    cout << endl;  }}string Huff_Decode(Node huffTree[], int n,string s){  cout << "解碼后為：";  string temp = "",str="";//保存解碼后的字符串  for (int i = 0; i < s.size(); i++)  {    temp = temp + s[i];    for (int j = 0; j < n; j++)    {      if (temp == huffTree[j].code)      {        str=str+ huffTree[j].ch;        temp = "";        break;      }      else if (i == s.size()-1&&j==n-1&&temp!="")//全部遍歷后沒有      {        str= "解碼錯誤！";      }    }  }  return str;}int main(){  //編碼過程  const int n=5;  Node huffTree[2 * n];  string str[] = { "A", "B", "C", "D", "E"};  int w[] = { 30, 30, 5, 20, 15 };  Huff_Tree(huffTree, w, str, n);  Huff_Code(huffTree, n);  //解碼過程  string s;  cout << "輸入編碼：";  cin >> s;  cout << Huff_Decode(huffTree, n, s)<< endl;;  system("pause");  return 0;}

運行結果如下：

C++,哈夫曼,編碼,解碼