Burrows-Wheeler-Transformation
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| #include <algorithm>
#include <string>
#include <vector>
std::pair<std::string, int> encode(std::string s) {
if (s.empty()) return {"", 0};
std::vector<std::string> l;
for (int i = 0; i < s.length(); ++i) {
l.push_back(s.substr(s.length() - i, i) + s.substr(0, s.length() - i));
}
std::sort(l.begin(), l.end());
int idx = 0;
for (int i = 0; i < l.size(); ++i) {
if (l[i] == s) {
idx = i;
break;
}
}
std::string res;
for (const auto& x : l) {
res += x.back();
}
return {res, idx};
}
std::string decode(std::string s, int n) {
if (s.empty()) {
return s;
}
std::vector<std::string> l(s.length());
for (int i = 0; i < s.length(); ++i) {
for (int j = 0; j < s.length(); ++j) {
l[j] = s[j] + l[j];
}
std::sort(l.begin(), l.end());
}
return l[n];
}
|
