Huffman树
结点定义：
1 /* 2 * Huffman树结点定义 3 */ 4 struct Node 5 { 6 ElementType weight; // 结点的权值 7 struct Node *leftChild; // 结点的左指针 8 struct Node *rightChild; // 结点的右指针 9 };
根据给定权值数组，构建一个Huffman树：
1 /* 2 * 输出内存申请失败的消息 3 */ 4 void showFailureMessage() 5 { 6 printf("Memory allocate failure!\n"); 7 exit(-1); 8 } 9 10 /* 11 * 根据数组获取数组的长度 12 */ 13 int getArrayLength(ElementType weights[]) 14 { 15 } 16 17 /* 18 * 对程序运行中申请的内存空间做事后处理 19 */ 20 void destroy(struct Node **) 21 { 22 } 23 24 /* 25 * 为给定权值数组创建一个Huffman树，返回根结点指针 26 */ 27 Node * createHuffmanTree(ElementType weights[]) 28 { 29 /* 根据传入的数组初始化 */ 30 int arrayLength = getArrayLength(weights); 31 struct Node **nodePointerArray = (struct Node **)malloc(sizeof(struct Node *) * arrayLength); 32 if(nodePointerArray == NULL) 33 showFailureMessage(); 34 for(int index = 0; index < arrayLength; ++index) { // 初始化指针数组nodePointerArray，每个指针指向一个二叉树结点 35 nodePointerArray[index] = (struct Node *)malloc(sizeof(struct Node)); 36 if(nodePointerArray[index] == NULL) 37 showFailureMessage(); 38 nodePointerArray[index]->weight = weights[index]; // 是树中各结点权值与传入的数组weights中元素一一对应 39 nodePointerArray[index]->leftChild = nodePointerArray[index]->rightChild = NULL; 40 } 41 42 /* 在初始化基础上进行(数组长度-1)次操作构造Huffman树 */ 43 struct Node * rootNode = NULL; 44 for(int index = 0; index < arrayLength; ++index) { 45 /* 找到自index后的最小值和次小值索引 */ 46 int lowestIndex = index; 47 int lowSecondIndex = index + 1; 48 for(int innerIndex = lowSecondIndex; innerIndex < arrayLength; ++innerIndex) { 49 if(nodePointerArray[innerIndex]->weight < nodePointerArray[lowestIndex]->weight) { 50 lowSecondIndex = lowestIndex; 51 lowestIndex = innerIndex; 52 } else if(nodePointerArray[innerIndex]->weight < nodePointerArray[lowSecondIndex]->weight) { 53 lowSecondIndex = innerIndex; 54 } 55 } 56 57 /* 将最小值和次小值所对应的结点(或子树的根结点)生成一颗二叉树 */ 58 rootNode = (struct Node *)malloc(sizeof(struct Node)); 59 if(rootNode == NULL) 60 showFailureMessage(); 61 rootNode->weight = nodePointerArray[lowestIndex]->weight + nodePointerArray[lowSecondIndex]->weight; 62 rootNode->leftChild = nodePointerArray[lowestIndex]; 63 rootNode->rightChild = nodePointerArray[lowSecondIndex]; 64 65 /* 此次生成二叉树后，对本次循环的索引值、最小值的索引值、次小值的索引值 66 * 所对应的结点做事后处理(此处巧用最小值和次小值所在结点需要移除) */ 67 nodePointerArray[lowestIndex] = rootNode; 68 nodePointerArray[lowSecondIndex] = nodePointerArray[index]; 69 nodePointerArray[index] = NULL; 70 } 71 destroy(nodePointerArray); 72 73 return rootNode; 74 }
Huffman树求得树中各字符编码：
1 /** 2 * 由给定的编码Huffman树求得树中各字符编码的算法，并分析器复杂度 3 **/ 4 void HuffmanCode(Node *root, int index) 5 { 6 static int code[SIZE]; // code存放字符编码，其长度等于树的深度 7 if(root != NULL) { 8 if(root->leftChild == NULL && root->rightChild == NULL) { 9 cout << "Weight：" << root->data << " coding："; 10 for(int in = 0; in < SIZE; ++in) // 输出叶子结点的编码 11 cout << code[in]; 12 count << endl; 13 } else { 14 code[index] = 0; 15 HuffmanCode(root->leftChild, (index + 1)); // 对左子树搜索 16 code[index] = 1; 17 HuffmanCode(root->rightChild, (index + 1)); // 对右子树搜索 18 } 19 } 20 }
OK哒！O(∩_∩)O哈！
