数据结构(c)--哈夫曼树解码

哈夫曼树解码

题目:

哈夫曼树 图

(从网上找的一张图...)

1.权重值越小的结点就在最下面 比如图中的B、C

2.图中的空结点 在我的代码中用'#'表示

完整代码

#include <stdio.h>
#define LeafCount 16
#define MaxWeight 100

typedef struct Node {
	int weight;
	char key;
	struct Node* lChild;
	struct Node* rChild;
}node;

typedef struct NodeArr {
	struct Node* nodes[LeafCount];
	int endIndex;
}nodeArr;

void AddNode(nodeArr*, node*);

nodeArr* InitNode(char chars[],float* weightArr) {
	int len = strlen(chars);
	nodeArr* arr = malloc(sizeof(nodeArr) * len);
	if (arr) {
		arr->endIndex = -1;
		for (int i = 0; i < LeafCount; i++) {
			node* tmp = malloc(sizeof(node));
			if (tmp) {
				tmp->key = chars[i];
				tmp->weight =*(weightArr+i) * 40;
				AddNode(arr,tmp);
			}
		}
	}
	return arr;
}

/// <summary>
/// 按照从大到小的顺序添加结点  最小的结点在最后  用于之后要取出
/// </summary>
/// <param name="arr"></param>
/// <param name="nod"></param>
void AddNode(nodeArr* arr,node* nod) {
	node* tmp;
	int i;
	for (i = arr->endIndex; i >-1; i--) {
		if (arr->nodes[i]->weight > nod->weight) {
			break;
		}
		if (arr->endIndex >= LeafCount)
		{
			printf("添加失败,超出了索引范围");
			return;
		}
		arr->nodes[i + 1] = arr->nodes[i];
	}
	arr->nodes[i + 1] = nod;
	arr->endIndex += 1;
}

/// <summary>
/// 根据上面的添加 可得：权重值最小的结点在最后一个
/// </summary>
/// <param name="arr"></param>
/// <returns></returns>
node* PopMinNode(nodeArr* arr) {
	return arr->nodes[arr->endIndex--];
}

/// <summary>
/// 构建哈夫曼树  取最小的两个结点 作为一个新结点的左孩子和右孩子
/// </summary>
/// <param name="arr"></param>
/// <returns></returns>
node* HuffmanTree(nodeArr* arr) {
	node* newNod = malloc(sizeof(node));
	while (arr->endIndex !=0) {
		node* minNod = PopMinNode(arr);
		node* minSecNod = PopMinNode(arr);
		newNod = malloc(sizeof(node));
		if (newNod) {
			newNod->key = '#';//用于解码判断  当key=='#' 表示这是个不含【编码值】的结点
			newNod->weight = minNod->weight + minSecNod->weight;
			newNod->lChild = minNod;
			newNod->rChild = minSecNod;
			AddNode(arr, newNod);
		}
	}

	return newNod;
}

void HuffmanDecode(node* root,char code[]) {
	node* p = root;
	int endIndex = strlen(code);
	int startIndex = 0;
	while (startIndex < endIndex) {
		char direct=code[startIndex];
		if (direct == '0') {//找左孩子     二进制编码中 0表示左孩子，1表示右孩子
			p = p->lChild;
		}
		else {
			p = p->rChild;
		}
		if (p->key != '#') {//不是空结点 表示是编码
			printf("%c", p->key);
			p = root;//继续下一个编码的匹配  重新从根节点继续解码
		}
		startIndex++;
	}
}


int main() {
	char character[] = { 'a','b','c','d','e','h','i','l','m','n','o','s','t','u','w','y'};
	float weights[] = { 0.1,0.05,0.025,0.05,0.15,0.075,0.025,0.05,0.05,0.075,0.025,0.05,0.15,0.025,0.075,0.025 };
	nodeArr* arr = InitNode(character, weights);
	node* root=HuffmanTree(arr);
	char* code = "0110000101011110011001001000010110000110011111110100110001011010001010000001011110010010111011111010010111101110001010000001111000110100101011001100000";
	
	HuffmanDecode(root, code);
	printf("\n");
	system("Pause");
}

运行结果