Huffman Tree -- Huffman编码

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
typedef struct HuffmanTree
{
	int weight;
	int parent, lchild, rchild;
}HuffmanTree;
typedef struct CodeNode
{
	int ch;
	char bits[4+1];
}CodeNode;
void SelectMin(HuffmanTree tree[], int len, int * pos1, int* pos2)
{
	int min=255;
	int i, j;
	*pos1=0;
	*pos2=0;
	for(i=0; i<len; i++)
	{
		if(tree[i].parent==-1)
			if(min>tree[i].weight)
			{
			min=tree[i].weight;
			*pos1=i;
		}
	}
   min=255;
   for(j=0; j<len; j++)
   {
		if(j==*pos1)
			continue;
		if(tree[j].parent==-1)
			if(min>tree[j].weight)
			{
				min=tree[j].weight;
				*pos2=j;
		}
	}
}
void CreateHuffmanTree(HuffmanTree tree[], int n)
{
	int m=2*n;
	int i;
	for(i=n; i<m-1; i++)
	{
		int pos1, pos2;
		HuffmanTree node;
		SelectMin(tree, i, &pos1, &pos2);
		printf("pos1=%d,pos2=%d\n", pos1, pos2);
		node.weight=tree[pos1].weight+tree[pos2].weight;
		tree[pos1].parent=i;
		tree[pos2].parent=i;
		node.lchild=pos1;
		node.rchild=pos2;
		node.parent=-1;
		tree[i]=node;
	}
}
void HuffmanEncoding(HuffmanTree tree[])
{
	int c, p, i;
	int start;
	char cd[4+1];
	cd[4]='\0';
	for(i=0; i<4; i++)
	{
		printf("\n");
		printf("%d",tree[i].weight);
		printf(":");
		start=4;
		c=i;
		while((p=tree[c].parent)!=-1)
		{
			if(tree[p].lchild==c)
			{
				cd[--start]='0';
			}
			else
			{
				cd[--start]='1';
			}
		c=p;
		}
		printf(&cd[start]);
	}
}
int main(int argc, char* argv[])
{
	HuffmanTree tree[4*2];
	int i, j;
	for(i=0; i<4; i++)
	{
		tree[i].lchild=-1;
		tree[i].rchild=-1;
		tree[i].parent=-1;
	}
	printf("请输入哈夫曼树叶子结点的权值: \n");
	for(i=0; i<4; i++)     //读入叶子结点的权值
	{
		int weight;
		scanf("%d",&weight);
		tree[i].weight=weight;
	}
	CreateHuffmanTree(tree, 4);
	for(j=0; j<2*4-1; j++)
	{
		printf("tree[%d]:weight=%d \n", j, tree[j].weight);
	}
	HuffmanEncoding(tree);
	return 0;
}