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4kyu: add „Shortest Knight Path“
• also move ISBN10 validation to correct language section Signed-off-by: Matej Focko <mfocko@redhat.com>
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2 changed files with 143 additions and 1 deletions
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4kyu/shortest_knight_path/solution.cpp
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141
4kyu/shortest_knight_path/solution.cpp
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#include <cassert>
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#include <deque>
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#include <iostream>
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#include <string>
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#include <vector>
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namespace {
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int convert_column(char x) { return x - 'a'; }
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int convert_row(char y) { return y - '1'; }
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template <typename T> bool in_range(const T &x, const T &min, const T &max) {
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return min <= x && x < max;
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}
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template <typename T> using table_t = std::vector<std::vector<T>>;
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static const std::vector<std::pair<int, int>> dpos{
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{-2, 1}, {-2, -1}, {-1, 2}, {-1, -2}, {1, 2}, {1, -2}, {2, 1}, {2, -1}};
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static const int dpos_size = static_cast<int>(dpos.size());
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class position_t;
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std::ostream &operator<<(std::ostream &stream, const position_t &pos);
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class position_t {
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int _x, _y;
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public:
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position_t(int x, int y) : _x(x), _y(y) {}
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position_t(const std::pair<int, int> &coords)
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: _x(coords.first), _y(coords.second) {}
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position_t(const std::string &position)
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: _x(convert_column(position[0])), _y(convert_row(position[1])) {}
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int x() const { return _x; }
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int y() const { return _y; }
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bool in_bounds() const { return in_range(_x, 0, 8) && in_range(_y, 0, 8); }
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template <typename T> T &in(table_t<T> &table) const { return table[_y][_x]; }
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bool operator==(const position_t &other) const {
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return _x == other._x && _y == other._y;
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}
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bool operator!=(const position_t &other) const {
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return _x != other._x || _y != other._y;
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}
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position_t operator+(const position_t &other) const {
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return {_x + other._x, _y + other._y};
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}
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};
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std::ostream &operator<<(std::ostream &stream, const position_t &pos) {
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stream << static_cast<char>('a' + pos.x())
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<< static_cast<char>('1' + pos.y());
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return stream;
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}
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class adjacent_iterator {
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const position_t pos;
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int i;
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position_t position() const { return pos + position_t(dpos[i]); }
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adjacent_iterator &next() {
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do {
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i++;
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} while (i < dpos_size && !position().in_bounds());
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return *this;
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}
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public:
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adjacent_iterator(position_t pos) : pos(pos), i(-1) { next(); }
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adjacent_iterator(position_t pos, int i) : pos(pos), i(i) {}
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bool operator!=(const adjacent_iterator &other) const {
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return pos != other.pos || i != other.i;
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}
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adjacent_iterator &operator++() { return next(); }
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position_t operator*() const { return position(); }
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};
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class adjacent {
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const position_t &pos;
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public:
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adjacent(const position_t &pos) : pos(pos) {}
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adjacent_iterator begin() const { return {pos}; }
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adjacent_iterator end() const { return {pos, dpos_size}; }
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};
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} // namespace
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int knight(std::string start, std::string finish) {
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position_t src(start);
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position_t dst(finish);
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// construct table
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table_t<int> distances(8, std::vector<int>(8, -1));
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src.in(distances) = 0;
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// run BFS and break once ‹finish› is found
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std::deque<position_t> queue{src};
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while (!queue.empty()) {
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position_t pos = queue.front();
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queue.pop_front();
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int current_distance = pos.in(distances);
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for (const auto &next_pos : adjacent(pos)) {
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next_pos.in(distances) = current_distance + 1;
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queue.push_back(next_pos);
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if (next_pos == dst) {
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// We have just set distance to the seeked position
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queue.clear();
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break;
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}
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}
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}
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// return the distance to ‹finish›
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return dst.in(distances);
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}
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int main() {
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// position_t p("b8");
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// std::cout << "Constructed from string: " << p << "\n";
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// std::cout << "===adjacent===\n";
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// for (auto pos : adjacent(p)) {
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// std::cout << pos << "\n";
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// }
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assert(knight("a1", "c1") == 2);
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assert(knight("a1", "f1") == 3);
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assert(knight("a1", "f3") == 3);
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assert(knight("a1", "f4") == 4);
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assert(knight("a1", "f7") == 5);
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return 0;
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}
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@ -40,6 +40,7 @@
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- [Matrix Determinant](https://www.codewars.com/kata/52a382ee44408cea2500074c) - [solution](4kyu/matrix_determinant)
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- [Infix to Postfix Converter](https://www.codewars.com/kata/52e864d1ffb6ac25db00017f) - [solution](4kyu/infix_to_postfix_converter)
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- [Range Extraction](https://www.codewars.com/kata/51ba717bb08c1cd60f00002f) - [solution](4kyu/range_extraction)
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- [Shortest Knight Path](https://www.codewars.com/kata/549ee8b47111a81214000941) - [solution](4kyu/shortest_knight_path)
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### JS
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- [int32 to IPv4](https://www.codewars.com/kata/52e88b39ffb6ac53a400022e) - [solution](5kyu/i32_to_ipv4)
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- [Convert A Hex String To RGB](https://www.codewars.com/kata/5282b48bb70058e4c4000fa7) - [solution](5kyu/convert_a_hex_string_to_rgb)
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- [ISBN-10 Validation](https://www.codewars.com/kata/51fc12de24a9d8cb0e000001) - [solution](5kyu/isbn10_validation)
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### C++
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- [Greed is Good](https://www.codewars.com/kata/5270d0d18625160ada0000e4) - [solution](5kyu/greed_is_good)
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- [Snakes and Ladders](https://www.codewars.com/kata/587136ba2eefcb92a9000027) - [solution](5kyu/snakes_and_ladders)
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- [The Clockwise Spiral](https://www.codewars.com/kata/536a155256eb459b8700077e) - [solution](5kyu/the_clockwise_spiral)
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- [ISBN-10 Validation](https://www.codewars.com/kata/51fc12de24a9d8cb0e000001) - [solution](5kyu/isbn10_validation)
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### Python
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