哈夫曼编码是最基本的字符压缩编码。对文本进行哈夫曼编码后再进行信息通讯可以大大提高信道利用率,缩短信息传输时间,降低传输成本。但是,这要求在发送端通过一个编码系统对待传数据预先编码;在接收端将传来的数据进行译码(复原)。 请设计一个程序,输入一行字符文本串(最大长度为10000个字符),构造其哈夫曼编码。根据需要(传输前)选择对字符文本进行编码(将字符文本转换为哈夫曼0-1编码),或对已编码的数据(接收后)进行译码(将0-1编码还原为字符文本)。
具体:
(1)初试化(I):读入一行文本,根据字符分布建立哈夫曼树,构造字符的哈夫曼编码(用于编码和译码),输出“Huffman code established!“”;
(2)编码(C):使用得到的哈夫曼编码对原始字符文本进行编码,输出;
(3)译码(D)::对编码后的0-1文本进行译码(还原为原来的字符文本),输出;
(4)退出(X):结束;注:如果编码或译码时,哈夫曼编码还没建立,应提示"Huffman code does not exist!”
例如:
样例输入:
I
Welcome to the school of computer science and technology.
C
D
11011001100100001000101101110111001001011100001101110111010000001110010000101011001101111010001000101111100011100111000111110101011101000011101101101000000111011111000100111101101110001100000110100100001010011111011111101010
X
样例输出:
Huffman code established!
11011001100100001000101101110111001001011100001101110111010000001110010000101011001101111010001000101111100011100111000111110101011101000011101101101000000111011111000100111101101110001100000110100100001010011111011111101010
Welcome to the school of computer science and technology.
要注意:
string不能malloc,要用new! string不能malloc,要用new! string不能malloc,要用new!
就是因为这个,codeblocks上边可以运行通过,OJ上不行,两天的段错误啊……
建立哈夫曼树的方法:
1.找到两个权值最小的点(若权值一样,则选择前面的),然后将这两个点连接到一个“根”上(根的权值是两个点权值之和),将“根”放到原序列最后,将选择的两个点从原序列删除(原序列指删除重复字符后的给定序列);
2.重复上述操作,直至原序列剩余一个点,将其标记为根节点。
包括空格的字符串这样输入:
getchar();
char c;
scanf("%c",&c);
int i=0;
while(c!='\n')
{
str[i]=c;
i++;
scanf("%c",&c);
}
len=i;
完整代码如下:
#pragma GCC optimize(3,"Ofast","inline")
#pragma G++ optimize(3)
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
typedef pair<int,int> pii;
typedef queue<int> q_i;
typedef queue<string> q_s;
typedef queue<double> q_d;
typedef queue<ll> q_ll;
typedef queue<char> q_c;
typedef priority_queue<int> pq_i;
typedef priority_queue<string> pq_s;
typedef priority_queue<double> pq_d;
typedef priority_queue<ll> pq_ll;
typedef stack<int> s_i;
typedef stack<string> s_s;
typedef stack<double> s_d;
typedef stack<ll> s_ll;
typedef stack<char> s_c;
typedef map<ll,ll> m_ll_ll;
typedef map<int,ll> m_i_ll;
typedef map<string,ll> m_s_ll;
typedef map<char,int> m_c_i;
typedef map<char,ll> m_c_ll;
#define rep(i,l,r) for(ll i=l;i<=r;i++)
#define per(i,l,r) for(ll i=r;i>=l;i--)
#define eif else if
#define N 3005
#define mm(dp) memset(dp,0,sizeof(dp))
#define mm1(dp) memset(dp,-1,sizeof(dp))
#define mm2(dp) memset(dp,0x3f,sizeof(dp))
#define IT set::iterator
#define fs(n) fixed<< setprecision(n)
#define inf 0x3f3f3f3f
const double e=2.71828182845;
const double pi = acos(-1.0);
map<char,int>mapp;
map<char,string>mapp1;
typedef struct
{
string s1;
int num;
}STU;
typedef struct
{
string s1,s0;
int num;
}STU1;
bool cmp(STU x,STU y)
{
return x.num>y.num;
}
typedef struct node
{
string data;
struct node *left,*right;
}HuffmanTreeNode,*PtrHuffman;
class Haffman
{
public:
PtrHuffman head=NULL;
PtrHuffman p[100005];
void create1(int nm,STU *stu)
{
int u=0;
rep(i,1,nm)
{
PtrHuffman t=new HuffmanTreeNode;
t->data = stu[i].s1;
t->left = t->right = NULL;
p[i]= t;
}
rep(i,1,nm-1)
{
int fi=inf,se=inf;
int fi1=0,se1=0;
rep(j,1,nm+u)
{
if(stu[j].num>0&&stu[j].num<fi)
{
fi=stu[j].num;
fi1=j;
}
}
rep(j,1,nm+u)
{
if(stu[j].num>0&&stu[j].num<se&&j!=fi1)
{
se=stu[j].num;
se1=j;
}
}
PtrHuffman q=new HuffmanTreeNode;
q->data=p[fi1]->data+p[se1]->data;
q->left=p[fi1];
q->right=p[se1];
u++;
stu[nm+u].s1=stu[fi1].s1+stu[se1].s1;
stu[nm+u].num=stu[fi1].num+stu[se1].num;
p[nm+u]=q;
stu[fi1].num=-1;
stu[se1].num=-1;
head=q;
}
}
void bianli(struct node *t1,int u)
{
if(t1==NULL)
return;
if(u==0)
cout<<t1->data<<endl;
else
{
cout<<u<<" ";
cout<<t1->data<<endl;
}
bianli(t1->left,u+1);
bianli(t1->right,u+1);
}
void bianli1(struct node *t1,char ch,string str)
{
if(t1==NULL)
return;
string s1="";
s1+=ch;
string ss=t1->data;
if(ss==s1)
{
mapp1[ch]=str;
return;
}
else
{
string s=t1->data;
int len=s.size();
int flag=0;
rep(i,0,len)
{
if(s[i]==ch)
{
flag=1;
break;
}
}
if(flag==0)
return;
else
{
bianli1(t1->left,ch,str+"0");
bianli1(t1->right,ch,str+"1");
}
}
}
STU1 bianli2(struct node *t1,string str)
{
if(t1->data.size()==1)
{
STU1 stu;
stu.s1=t1->data;
int len=str.size();
stu.s0=str;
return stu;
}
char ch=str[0];
int len=str.size();
str=str.substr(1,len-1);
if(ch=='0')
{
return bianli2(t1->left,str);
}
if(ch=='1')
{
return bianli2(t1->right,str);
}
}
};
int len;
int main()
{
//ios::sync_with_stdio(false);
//cin.tie(0);
//cout.tie(0);
Haffman ha;
char str[10005];
int uu=0;
while(1)
{
char ch;
cin>>ch;
if(ch=='X')
break;
eif(ch=='I')
{
getchar();
char c;
scanf("%c",&c);
int i=0;
while(c!='\n')
{
str[i]=c;
i++;
scanf("%c",&c);
}
len=i;
string ss="";
rep(i,0,len-1)
{
if(mapp[str[i]]==0)
{
mapp[str[i]]=1;
ss+=str[i];
}
eif(mapp[str[i]]!=0)
{
mapp[str[i]]++;
}
}
int len1=ss.size();
STU stu[10005];
rep(i,0,len1-1)
{
string s0="";
char c=ss[i];
s0+=c;
stu[i+1].s1=s0;
stu[i+1].num=mapp[c];
}
ha.create1(len1,stu);
cout<<"Huffman code established!"<<endl;
uu=1;
}
eif(ch=='C')
{
if(uu==0)
{
cout<<"Huffman code does not exist!"<<endl;
}
else{
rep(i,0,len-1)
{
char cc=str[i];
ha.bianli1(ha.head,cc,"");
cout<<mapp1[str[i]];
}
cout<<endl;
}}
eif(ch=='D')
{
if(uu==0)
{
cout<<"Huffman code does not exist!"<<endl;
}
else{
string s2;
cin>>s2;
while(1)
{
if(s2=="")
break;
STU1 huan=ha.bianli2(ha.head,s2);
cout<<huan.s1;
s2=huan.s0;
}
cout<<endl;
}}
}
return 0;
}