133 lines
2.9 KiB
C++
133 lines
2.9 KiB
C++
/*
|
|
* Copyright © 2004-2011 Ondra Kamenik
|
|
* Copyright © 2019 Dynare Team
|
|
*
|
|
* This file is part of Dynare.
|
|
*
|
|
* Dynare is free software: you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation, either version 3 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* Dynare is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with Dynare. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include "pascal_triangle.hh"
|
|
|
|
#include <iostream>
|
|
#include <mutex>
|
|
|
|
void
|
|
PascalRow::setFromPrevious(const PascalRow &prev)
|
|
{
|
|
k = prev.k + 1;
|
|
clear();
|
|
prolong(prev);
|
|
}
|
|
|
|
/* This prolongs the PascalRow. If it is empty, we set the first item
|
|
⎛k+1⎞
|
|
to k+1, which is ⎝ k ⎠, which is the second item in the real
|
|
⎛k⎞
|
|
pascal row, which starts from ⎝k⎠=1. Then we calculate
|
|
other items from the provided row which must be the one with k-1.
|
|
*/
|
|
void
|
|
PascalRow::prolong(const PascalRow &prev)
|
|
{
|
|
if (size() == 0)
|
|
push_back(k+1);
|
|
int last = back();
|
|
for (unsigned int i = size(); i < prev.size(); i++)
|
|
{
|
|
last += prev[i];
|
|
push_back(last);
|
|
}
|
|
}
|
|
|
|
void
|
|
PascalRow::prolongFirst(int n)
|
|
{
|
|
// TODO: check n = 1
|
|
for (int i = static_cast<int>(size())+2; i <= n; i++)
|
|
push_back(i);
|
|
}
|
|
|
|
void
|
|
PascalRow::print() const
|
|
{
|
|
std::cout << "k=" << k << std::endl;
|
|
for (unsigned int i = 0; i < size(); i++)
|
|
std::cout << operator[](i) << ' ';
|
|
std::cout << std::endl;
|
|
}
|
|
|
|
namespace PascalTriangle
|
|
{
|
|
namespace // Anonymous namespace that is a functional equivalent of “private”
|
|
{
|
|
std::vector<PascalRow> tr(1);
|
|
std::mutex mut; // For protecting the triangle from concurrent modifications
|
|
|
|
int
|
|
max_n()
|
|
{
|
|
return static_cast<int>(tr[0].size()+1);
|
|
}
|
|
|
|
int
|
|
max_k()
|
|
{
|
|
return static_cast<int>(tr.size());
|
|
}
|
|
}
|
|
|
|
void
|
|
ensure(int n, int k)
|
|
{
|
|
// Add along n
|
|
if (n > max_n())
|
|
{
|
|
std::lock_guard<std::mutex> lk{mut};
|
|
tr[0].prolongFirst(n);
|
|
for (int i = 2; i <= max_k(); i++)
|
|
tr[i-1].prolong(tr[i-2]);
|
|
}
|
|
|
|
if (k > max_k())
|
|
{
|
|
std::lock_guard<std::mutex> lk{mut};
|
|
for (int i = max_k()+1; i <= k; i++)
|
|
{
|
|
tr.emplace_back();
|
|
tr.back().setFromPrevious(tr[i-2]);
|
|
}
|
|
}
|
|
}
|
|
|
|
int
|
|
noverk(int n, int k)
|
|
{
|
|
// TODO: raise exception if out of bounds
|
|
if (n-k < k)
|
|
k = n-k;
|
|
if (k == 0)
|
|
return 1;
|
|
ensure(n, k);
|
|
return (tr[k-1])[n-1-k];
|
|
}
|
|
|
|
void
|
|
print()
|
|
{
|
|
for (const auto &i : tr)
|
|
i.print();
|
|
}
|
|
}
|