哈夫曼编码:
根据给定的哈夫曼树,从每个叶子节点出发回溯到树根,逆向找出最优二叉树中叶子节点的编码。
代码如下:
#define MAXLEAFNUM 50 #include<malloc.h> #include<cstring> typedef struct node{ char ch;//节点表示的字符 int weight;//权值 int parent;//父节点下标(默认为零) int lchild,rchild;//左右孩子下标(默认为零) }HuffmanTree[2*MAXLEAFNUM]; typedef char* HuffmanCode[MAXLEAFNUM+1]; /*从HT中选择parent为0且weight最小的两棵树,其序列号为s1和s2*/ void select(HuffmanTree HT,int n,int &s1,int &s2) { int i,min2; int min1=min2=32768; for(i=0;i<n;i++) { if(HT[i].parent==0) { if(HT[i].weight<min1){ min2=min1; min1=HT[i].weight; }else if(HT[i].weight<min2) { min2=HT[i].weight; } } } s1=min1; s2=min2; } /*构造最优二叉树*/ void createHTree(HuffmanTree HT,char *c,int *w,int n) { int i,s1,s2;// if(n<=1)return; for(i=1;i<=n;i++)//初始化 { HT[i].ch=c[i-1]; HT[i].weight=w[i-1]; HT[i].parent=HT[i].lchild=HT[i].rchild=0; } for(;i<2*n;i++)// { HT[i].parent=HT[i].lchild=HT[i].rchild=0; } for(i=n+1;i<2*n;i++) { select(HT,i-1,s1,s2); HT[s1].parent=i; HT[s2].parent=i; HT[i].lchild=s1; HT[i].rchild=s2; HT[i].weight=HT[s1].weight+HT[s2].weight; } } /*编码*/ void HuffmanCoding(HuffmanTree HT,HuffmanCode HC,int n) {//n个叶子结点在哈夫曼树HT中的下标为1~n,第i(1<=i<=n)个叶子的编码存放HC[i]中 char *cd;int i,start,c,f; if(n<=1) return; cd=(char*)malloc(n*sizeof(char)); cd[n-1]='\0'; for(i=1;i<=n;i++) { start=n-1; for(c=i,f=HT[i].parent;f!=0;c=f,f=HT[f].parent) if(HT[f].lchild==c) cd[--start]='0'; else cd[--start]='1'; HC[i]=(char*)malloc((n-start)*sizeof(char)); strcpy(HC[i],&cd[start]); } free(cd); } /*用最优二叉树进行译码*/ void Decoding(HuffmanTree HT,int n,char *buff) { int p=2*n-1; while(*buff) { if((*buff)=='0') p=HT[p].lchild; else p=HT[p].rchild; if(HT[p].lchild==0&&HT[p].lchild==0) { pritnf("%c",HT[p].ch); p=2*n-1; } buff++; } } int main() { return 0; }