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BWT.cpp
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BWT.cpp
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#pragma GCC optimize("O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,tune=native")
#pragma GCC target("avx2")
#include <fstream>
#include <iostream>
#include <algorithm>
#include <vector>
#include "utils.h"
using namespace std;
typedef long long LL;typedef long long ll;typedef unsigned long long uLL;typedef unsigned long long ull;typedef unsigned int uint;typedef unsigned char uchar;typedef long double ld;typedef long double Ld;
// BWT
vector<char> bwt(vector<char> &s) {
int n = s.size() + 1;
s.push_back('$');
vector<int> starts(n);
for (int i = 0; i < n; ++i) starts[i] = i;
sort(starts.begin(), starts.end(), [&s, n](int x, int y) {
int res;
for (int i = 0; i < n; ++i) {
res = s[(x + i) % n] - s[(y + i) % n];
if (res != 0) return res < 0;
}
return false;
});
vector<char> res(n);
for (int i = 0; i < n; ++i) res[i] = s[(starts[i] + n - 1) % n];
return res;
}
// Inverse BWT
vector<char> ibwt(vector<char> &s) {
int n = s.size(),
k = distance(s.begin(), find(s.begin(), s.end(), '$'));
vector<pair<char, int>> permutation(n);
for (int i = 0; i < n; ++i) {
permutation[i].first = s[i];
permutation[i].second = i;
}
sort(permutation.begin(), permutation.end());
vector<char> res(n - 1);
for (int i = 0; i < n - 1; ++i) {
res[i] = permutation[k].first;
k = permutation[k].second;
}
return res;
}
// Compression
vector<char> compress(vector<char> &s) {
int n = s.size(), count = 1;
vector<char> res {s[0]};
for (int pos = 1; pos < n; ++pos, ++count) {
if (s[pos - 1] != s[pos]) {
if (count > 1) {
string count_str = to_string(count);
for (int i = 0; i < count_str.size(); ++i) {
res.push_back(count_str[i]);
}
}
count = 0;
res.push_back(s[pos]);
}
}
if (count > 1) {
string count_str = to_string(count);
for (int i = 0; i < count_str.size(); ++i) {
res.push_back(count_str[i]);
}
}
return res;
}
int bwtTest() {
cout << "Starting BWT test..." << endl;
ifstream input("../src/BWT/BWT_test_large.txt");
vector<char> text_vector = readSeq(input);
input.close();
string text(text_vector.begin(), text_vector.end());
cout << "Encrypting..." << endl;
auto encrypted_vector = bwt(text_vector);
cout << "Encrypted" << endl;
string encrypted_text(encrypted_vector.begin(), encrypted_vector.end());
cout << "Compressing..." << endl;
auto compressed_vector = compress(encrypted_vector);
cout << "Compressed" << endl;
string compressed_text(compressed_vector.begin(), compressed_vector.end());
cout << "Decrypting..." << endl;
auto decrypted_vector = ibwt(encrypted_vector);
cout << "Decrypted" << endl;
string decrypted_text(decrypted_vector.begin(), decrypted_vector.end());
// cout << text.size() << " -> " << encrypted_vector.size() << " -> " << compressed_vector.size() << endl;
// cout << text << endl << endl;
// cout << encrypted_text << endl << endl;
// cout << compressed_text << endl << endl;
// cout << decrypted_text << endl << endl;
auto compressed_raw_vector = compress(text_vector);
string compressed_raw_text(compressed_raw_vector.begin(), compressed_raw_vector.end());
cout << text.size() << " -> " << encrypted_vector.size() << " -> " << compressed_vector.size() << " / " << compressed_raw_text.size() << endl;
cout << "Test End" << endl << endl;
}