//使用weigh数组构建一个huffman树
HuffmanTree CreateTree(int* weight, int n)
{
int total = 2 * n - 1;
HuffmanTree HT = (HuffmanTree)malloc(total * sizeof(HTNode));
if (!HT)
{
printf("HuffmanTree malloc faild!\n");
exit(-1);
}
int i;
//HT[0...n-1]存放的是需要编码的n个叶子节点
//初始情况下父节点和左右子节点都为-1
for (i = 0; i < n; ++i)
{
HT[i].parent = -1;
HT[i].lchild = -1;
HT[i].rchild = -1;
HT[i].weight = *weight;
weight++;
}
//HT[n ... 2n-2]存放的是中间构造的二叉树的节点
for (; i<total; ++i)
{
HT[i].parent = -1;
HT[i].lchild = -1;
HT[i].rchild = -1;
HT[i].weight = -1;
}
int min1, min2;
for (i = n; i < total; ++i)
{
SelectMin(HT, i, min1, min2);
HT[min1].parent = i;
HT[min2].parent = i;
HT[i].lchild = min1;
HT[i].rchild = min2;
HT[i].weight = HT[min1].weight + HT[min2].weight;
}
return HT;
}
void HuffmanCodding(HuffTree &hufftree,HuffCode &huffCode,int* w,int n) {
//建立哈夫曼树
int lchild, rchild;
int start;
int m = 2 * n - 1;//总结点个数
int i;
//初始化n个子节点
for (i = 1; i <=n; i++)
{
hufftree[i].weight = w[i];//权重赋值
hufftree[i].parent = 0;//无父节点
hufftree[i].lchild = 0;//无左孩子节点
hufftree[i].rchild = 0;//无右孩子节点
}
//初始化非叶子节点
for (i = n+1; i <=m; i++)
{
hufftree[i].weight = 0;
hufftree[i].parent = 0;
hufftree[i].lchild = 0;
hufftree[i].rchild = 0;
}
//使用n+1至m的节点建立哈夫曼树
for (i = n+1; i <=m; i++)
{
//这里从i-1开始，因为父节点也会不断地加入
SelectMin(hufftree,i-1,lchild);//拿到权重小的左节点下标
hufftree[lchild].parent = i;
//printf("lchild = %d-->parent = %d\n",lchild, hufftree[lchild].parent);
hufftree[i].lchild = lchild;
SelectMin(hufftree,i-1,rchild);//拿到权重小的右节点下标
//更新hufftree的各种数值
hufftree[rchild].parent = i;
//printf("rchild = %d-->parent = %d\n", rchild, hufftree[rchild].parent);
hufftree[i].rchild = rchild;
hufftree[i].weight = hufftree[lchild].weight + hufftree[rchild].weight;
//printf("parent = %d-->lchild = %d-->rchild = %d\n", hufftree[rchild].parent,lchild,rchild);
}
//逆向保存每个字符的哈夫曼编码
char *temp;//保存
//对于n个叶子节点
for ( i = 1; i <=n; i++)
{
temp = (char*)malloc(sizeof(char)*n);//暂时性地保存编码，逆向保存
temp[n - 1] = '\0';//最后保存的结束字符
int c = i;
int parentIndex;
start = n-1;//从结束字符的前一位开始，start指向的是填入的那个空
parentIndex = hufftree[i].parent;
while (parentIndex!=0)//判断父节点是否有parent下标，是否为根节点
{
//printf("child = %d-->parent = %d\n", c, parentIndex);
if (hufftree[parentIndex].lchild == c)//说明该子节点是其父节点的左孩子
{
temp[--start] = '0';//保存‘0’字符
}
if (hufftree[parentIndex].rchild == c)//说明该子节点是其父节点的右孩子
{
temp[--start] = '1';
}
c = parentIndex;//!!!!坑爹2，这个也要更新
parentIndex = hufftree[parentIndex].parent;//迭代，更新为目前节点的父节点
}
//获取到总的编码后
int length = n-start;//总长度
huffCode[i] = (char*)malloc(sizeof(char)*length);
//复制！！注意是从start开始复制
strcpy(huffCode[i],&temp[start]);
free(temp);
}
}
