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Huffman_Class.cpp
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Huffman_Class.cpp
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class Huffman;
class Node {
Node* left;
Node* right;
vector<char> chars;
int count;
public:
Node(char c, int count);
Node(Node* a, Node* b);
int getCount();
void incCount();
bool isIn(char c);
bool isLeaf();
friend class Huffman;
};
class Huffman {
Node* root;
void makeTree(string& str);
string getCode(char c);
void initQue(vector<Node*>& que, string& str);
void popLeastTwo(vector<Node*>& que, Node* &one, Node* &two);
public:
string encode(string& str);
string decode(string& str);
};
Node::Node(char c, int count) {
chars.push_back(c);
this->count = count;
left = NULL;
right = NULL;
}
Node::Node(Node* a, Node* b) {
left = a;
right = b;
count = a->count + b->count;
for (int i = 0; i < a->chars.size(); i++)
chars.push_back(a->chars[i]);
for (int i = 0; i < b->chars.size(); i++)
chars.push_back(b->chars[i]);
}
int Node::getCount() {
return count;
}
bool Node::isIn(char c) {
for (int i = 0; i < chars.size(); i++)
if (chars[i] == c)
return true;
return false;
}
bool Node::isLeaf() {
if (left == NULL && right == NULL)
return true;
else
return false;
}
void Node::incCount() {
count++;
}
void Huffman::popLeastTwo(vector<Node*>& que, Node* &one, Node* &two) {
int nOne, nTwo;
if (que[0]->getCount() < que[1]->getCount()) {
one = que[0];
two = que[1];
nOne = 0;
nTwo = 1;
}
else {
one = que[1];
two = que[0];
nOne = 1;
nTwo = 0;
}
for (int i = 2; i < que.size(); i++) {
if (que[i]->getCount() < one->getCount()) {
two = one;
one = que[i];
nTwo = nOne;
nOne = i;
}
else if (que[i]->getCount() < two->getCount()) {
two = que[i];
nTwo = i;
}
}
if (nOne < nTwo) {
que.erase(que.begin() + nTwo);
que.erase(que.begin() + nOne);
}
else {
que.erase(que.begin() + nOne);
que.erase(que.begin() + nTwo);
}
}
void Huffman::initQue(vector<Node*>& que, string& str)
{
for (int i = 0; i < str.size(); i++) {
bool newone = true;
for (int j = 0; j < que.size(); j++) {
if (que[j]->isIn(str[i])) {
que[j]->incCount();
newone = false;
}
}
if (newone)
que.push_back(new Node(str[i], 1));
}
}
void Huffman::makeTree(string& str) {
vector<Node*> que;
Node* one, * two;
initQue(que, str);
while (que.size() > 1) {
popLeastTwo(que, one, two);
que.push_back(new Node(one, two));
}
root = que[0];
}
string Huffman::getCode(char c) {
Node* pNode;
pNode = root;
string rtstr = "";
while (!pNode->isLeaf()) {
if (pNode->left->isIn(c)) {
rtstr += "0";
pNode = pNode->left;
}
else {
rtstr += "1";
pNode = pNode->right;
}
}
return rtstr;
}
string Huffman::encode(string& str) {
makeTree(str);
string rtstr = "";
for (int i = 0; i < str.length(); i++)
rtstr += getCode(str[i]);
return rtstr;
}
string Huffman::decode(string& str) {
string rtstr = "";
Node* cur;
int i;
for (cur = root, i = 0; i < str.length(); i++) {
if (str[i] == '0')
cur = cur->left;
else
cur = cur->right;
if (cur->isLeaf()) {
rtstr += cur->chars[0];
cur = root;
}
}
return rtstr;
}
int main() {
Huffman myhuff;
string original = "Hello";
string encoded = myhuff.encode(original);
string decoded = myhuff.decode(encoded);
cout << original << endl;
cout << encoded << endl;
cout << decoded << endl;
}