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permutation.cpp
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101 lines (85 loc) · 2.78 KB
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#include "permutation.h"
#include <algorithm>
#include <iostream>
void Permutation::Permutation(const std::string& str, const std::string& prefix)
{
const int size = static_cast<int>(str.length());
if (size == 0)
{
std::cout << prefix << std::endl;
return;
}
for (int i = 0; i < size; ++i)
{
const std::string rem = str.substr(0, i) + str.substr(i + 1);
Permutation(rem, prefix + str[i]);
}
}
auto Permutation::ApplyPermutationWithAdditionalSpace(const std::vector<int>& permutation, const std::vector<char>& arr)
-> std::vector<char>
{
std::vector<char> result(arr.size());
for (int i = 0; i < static_cast<int>(arr.size()); ++i)
{
result[permutation[i]] = arr[i];
}
return result;
}
auto Permutation::ApplyPermutationBySwap(std::vector<int>& permutation, std::vector<char>& arr) -> std::vector<char>
{
for (int i = 0; i < static_cast<int>(arr.size()); ++i)
{
while (permutation[i] != i)
{
std::swap(arr[i], arr[permutation[i]]);
std::swap(permutation[i], permutation[permutation[i]]);
}
}
return arr;
}
auto Permutation::InversePermutation(const std::vector<int>& permutation, const std::vector<char>& arr)
-> std::vector<int>
{
std::vector<int> result(arr.size());
for (int i = 0; i < static_cast<int>(arr.size()); ++i)
{
result[permutation[i]] = i;
}
return result;
}
auto Permutation::NextPermutation(std::vector<int>& permutation) -> std::vector<int>
{
const auto inversionPoint = std::is_sorted_until(permutation.rbegin(), permutation.rend());
if (inversionPoint == permutation.rend())
{
return {};
}
const auto leastUpperBound = std::upper_bound(permutation.rbegin(), inversionPoint, *inversionPoint);
std::iter_swap(inversionPoint, leastUpperBound);
std::reverse(permutation.rbegin(), inversionPoint);
return permutation;
}
auto Permutation::PreviousPermutation(std::vector<int>& permutation) -> std::vector<int>
{
const auto inversionPoint = std::is_sorted_until(permutation.rbegin(), permutation.rend(), std::greater<>());
if (inversionPoint == permutation.rend())
{
return {};
}
const auto leastUpperBound = std::upper_bound(permutation.rbegin(), inversionPoint, *inversionPoint, std::greater<>());
std::iter_swap(inversionPoint, leastUpperBound);
std::reverse(permutation.rbegin(), inversionPoint);
return permutation;
}
auto Permutation::KthPermutation(std::vector<int>& permutation, int k) -> std::vector<int>
{
std::sort(permutation.begin(), permutation.end());
do
{
if (--k == 0)
{
return permutation;
}
} while (std::next_permutation(permutation.begin(), permutation.end()));
return {};
}