huffman 编码

/*
 * author : BoJing .Wang
 * time : Ang 1st,2011
 * goal : implement huffman code
 *
 */

#include <iostream>
#include <cstring>

using namespace std;

static int Code[20] = {
    12,34,35,42,14,57,51,31,42,98,
    52,76,62,95,64,73,82,70,69,67
};

struct MinValue{
    int frist; //最小值的下标
    int second; //次值的下标
    int x1;
    int x2;
};

struct Huffman{
    int value; //结点值
    int flag; //标记(0/1)
    int parent; //父结点的下标
    int right; //右孩子的下标
    int left; //左孩子的下标
};

struct EnCode{
    int value; //结点值
    int start; //编码开始位置
    int bit[10]; //编码
};

void InitHuffman(Huffman Node[],int n){
    for(int i = 0;i < 2*n-1;i ++){
    if(i < n) Node[i].value = Code[i];
    else Node[i].value = 0;   
        Node[i].flag = 0;
        Node[i].parent = 0;
       
        Node[i].left = -1;
        Node[i].right = -1;       
    }
}

//选择两个最小值
MinValue selectMin(Huffman Node[],int n,int t){
    MinValue mv = {100000,100000,0,0};

    for(int i = 0;i < n+t;i ++){
        if(Node[i].value < mv.frist && Node[i].flag == 0){
            mv.second = mv.frist;
            mv.x2 = mv.x1;
            mv.frist = Node[i].value;
            mv.x1 = i;
        }else if(Node[i].value < mv.second && Node[i].flag == 0){
            mv.second = Node[i].value;
            mv.x2 = i;
        }
    }
   
    return mv;
}

void CombineData(Huffman Node[],int n,int t,MinValue m){
    Node[m.x1].parent = n+t;
    Node[m.x2].parent = n+t;

    Node[m.x1].flag = 1;
    Node[m.x2].flag = 1;

    Node[n+t].value = Node[m.x1].value + Node[m.x2].value;
    Node[n+t].left = m.x1;
    Node[n+t].right = m.x2;

    return ;
}

void HuffmanCode(Huffman Node[],EnCode code[],int n){
    EnCode c;
    int child,parent;
    memset(&c,0,sizeof(c));

    for(int i = 0;i < n;i ++){
        child = i;
        parent = Node[child].parent;
        c.value = Node[child].value;
        c.start = n-11;
        while(parent){
            if(Node[parent].left == child)
                c.bit[c.start] = 0;
            else c.bit[c.start] = 1;
            c.start --;
            child = parent;
            parent = Node[child].parent;
        }

        for(int j = c.start+1;j < n-10;j ++){
            code[i].bit[j] = c.bit[j];
        }
        code[i].start = c.start;
        code[i].value = c.value;
    }
}

int main(){
    MinValue m;
    Huffman hufftree[40];
    EnCode code[20];

    InitHuffman(hufftree,20);
    for(int i = 0;i < 19;i ++){
        m = selectMin(hufftree,20,i);
        CombineData(hufftree,20,i,m);
    }

    HuffmanCode(hufftree,code,20);
    cout << "Huffman code as follow :" << endl;
    for(int i = 0;i < 20;i ++){
        cout << "value : "<<hufftree[i].value <<", code : ";
        for(int j = code[i].start+1;j < 10;j ++)
            cout << code[i].bit[j];
        cout << endl;
    }
    return 0;
}