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| #include <iostream>
#include <vector>
#include <list>
#include <map>
using namespace std;
class Node
{
public:
int count;
char symbol;
Node *left;
Node *right;
Node() { }
Node(char __symbol, int __count)
{
symbol = __symbol;
count = __count;
}
Node(Node *l, Node *r) // create parent
{
symbol = 0;
left = l;
right = r;
count = l->count + r->count;
}
static void Print(Node *root, int depth = 0)
{
if (!root) return;
if (root->symbol)
{
for (int i = 0; i < depth; i++)
cout << ".";
cout << root->symbol << endl;
}
else depth++;
Print(root->left, depth);
Print(root->right, depth);
}
};
void BuildTable(Node *root, vector<bool> &code, map<char, vector<bool>> &table) // dfs
{
if (root->left)
{
code.push_back(0); // left
BuildTable(root->left, code, table);
}
if (root->right)
{
code.push_back(1); // right
BuildTable(root->right, code, table);
}
if (root->symbol)
table[root->symbol] = code;
if (code.size())
code.pop_back();
}
bool SortNode(const Node *a, const Node *b)
{
return a->count < b->count;
}
string Decode(string &str, map<vector<bool>, char> &table) // flipped table: code - char pairs
{
string out = "";
vector<bool> code;
for (int i = 0; i < str.length(); i++)
{
code.push_back(str[i] == '0' ? false : true);
if (table[code])
{
out += table[code];
code.clear();
}
}
return out;
}
int main()
{
string raw = "SSSPPORTTTT";
map<char, int> symbols;
for (int i = 0; i < raw.length(); i++)
symbols[raw[i]]++;
list<Node*> trees;
map<char, int>::iterator itr;
for (itr = symbols.begin(); itr != symbols.end(); itr++)
{
Node *p = new Node(itr->first, itr->second); // key = symbol; value = count
trees.push_back(p);
}
while (trees.size() != 1)
{
trees.sort(SortNode);
Node *l = trees.front();
trees.pop_front();
Node *r = trees.front();
trees.pop_front();
Node *parent = new Node(l, r);
trees.push_back(parent);
}
Node *root = trees.front();
root->Print(root);
vector<bool> code; // buffer
map<char, vector<bool> > table;
BuildTable(root, code, table); // generate symbol-code key-value pair
// print codes
// print coded string
for (itr = symbols.begin(); itr != symbols.end(); itr++)
{
cout << itr->first << " - ";
for (int j = 0; j < table[itr->first].size(); j++)
cout << table[itr->first][j];
cout << endl;
}
string out = "";
// print coded string
for (int i = 0; i < raw.length(); i++)
for (int j = 0; j < table[raw[i]].size(); j++)
{
out += table[raw[i]][j] + '0';
cout << table[raw[i]][j];
}
cout << endl;
cout << out.c_str() << endl;
// decode
map<vector<bool>, char> ftable;
for (auto i = table.begin(); i != table.end(); i++)
ftable[i->second] = i->first;
cout << Decode(out, ftable).c_str() << endl;
while (true);
} |
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