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25b39a34fa
* [fix/docs]: Update backtracking/graph_coloring.cpp * Add CMakeLists.txt in backtracking folder * Add backtracking to CMakeLists.txt * fix: Fix build issues * docs: Various documentation fixes * fix: minimax.cpp issues * fix: sudoku_solve.cpp fixes * formatting source-code for8ffbbb35ce
* make he code neat and clean without global variables * fix 2 stars in comment * fix MSVC errors by forcing template parameter in function calls Note: This is identical to passing it as a function parameter, and may not be helpful * Update minimax.cpp * docs: minimax.cpp improvements * docs: Add Wikipedia link in minimax.cpp * fix: minimax.cpp vector fix * docs: fix Wikipedia link in minimax.cpp * docs: fix return statement in minimax.cpp * fix: sudoku_solve.cpp fixes * fix: more sudoku_solve.cpp fixes * fix: sudoku_solve.cpp fixes * fix: sudoku_solve.cpp * formatting source-code for13b5b9b829
* docs: update graph_coloring.cpp description * fix: use array instead of vector (minimax.cpp) * feat: add namespace (minimax.cpp) * docs: update namespace description (graph_coloring.cpp) * fix: graph_coloring.cpp * fix: sudoku_solve.cpp fixes * fix: graph_coloring.cpp * fix: minimax.cpp * fix: more sudoku_solve.cpp fixes * fix: more graph_coloring.cpp fixes * fix: graph_coloring.cpp fixes * fix: sudoku_solve.cpp fixes * fix: minimax.cpp * fix: sudoku_solve.cpp fixes * fix: too few template arguments (std::array) * fix: too few template arguments (std::array, minimax.cpp) * fix: narrowing conversion from double to int (minimax.cpp) * fix: excess elements in struct initializer (graph_coloring.cpp) * fix: no matching function (graph_coloring.cpp) * fix: graph_coloring.cpp issues/errors * fix: knight_tour.cpp issues/errors * fix: sudoku_solve.cpp issues/errors * [fix/docs]: Various fixes in graph_coloring.cpp * fix: More graph_coloring.cpp fixes * docs: Add initial comment block (sudoku_solve.cpp) * fix: Add return statement (knight_tour.cpp) * fix: array fixes (graph_coloring.cpp) * docs: documentation improvements (sudoku_solve.cpp) * docs: documentation improvements (knight_tour.cpp) * docs: documentation improvements (sudoku_solve.cpp) * docs: documentation improvements (graph_coloring.cpp) * docs: Documentation improvements (graph_coloring.cpp) Thanks, @kvedala! * docs: Documentation improvements (sudoku_solve.cpp) * docs: Document function parameter (sudoku_solve.cpp) * docs: Documentation improvements (knight_tour.cpp) * docs: Add long description (graph_coloring.cpp) * docs: Add long description (minimax.cpp) * docs: Add long description (sudoku_solve.cpp) * docs: Documentation improvements (knight_tour.cpp) * docs: Documentation improvements (sudoku_solve.cpp) * docs: Documentation improvements (minimax.cpp) * docs: More documentation improvements (minimax.cpp) * docs: Documentation improvements (sudoku_solve.cpp) * fix: sudoku_solve.cpp improvements Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com> Co-authored-by: Krishna Vedala <7001608+kvedala@users.noreply.github.com>
106 lines
3.1 KiB
C++
106 lines
3.1 KiB
C++
/**
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* @file
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* @brief [Knight's tour](https://en.wikipedia.org/wiki/Knight%27s_tour) algorithm
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*
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* @details
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* A knight's tour is a sequence of moves of a knight on a chessboard
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* such that the knight visits every square only once. If the knight
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* ends on a square that is one knight's move from the beginning
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* square (so that it could tour the board again immediately, following
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* the same path, the tour is closed; otherwise, it is open.
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*
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* @author [Nikhil Arora](https://github.com/nikhilarora068)
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* @author [David Leal](https://github.com/Panquesito7)
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*/
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#include <iostream>
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#include <array>
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/**
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* @namespace backtracking
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* @brief Backtracking algorithms
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*/
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namespace backtracking {
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/**
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* A utility function to check if i,j are valid indexes for N*N chessboard
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* @tparam V number of vertices in array
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* @param x current index in rows
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* @param y current index in columns
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* @param sol matrix where numbers are saved
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* @returns `true` if ....
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* @returns `false` if ....
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*/
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template <size_t V>
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bool issafe(int x, int y, const std::array <std::array <int, V>, V>& sol) {
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return (x < V && x >= 0 && y < V && y >= 0 && sol[x][y] == -1);
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}
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/**
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* Knight's tour algorithm
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* @tparam V number of vertices in array
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* @param x current index in rows
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* @param y current index in columns
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* @param mov movement to be done
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* @param sol matrix where numbers are saved
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* @param xmov next move of knight (x coordinate)
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* @param ymov next move of knight (y coordinate)
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* @returns `true` if solution exists
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* @returns `false` if solution does not exist
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*/
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template <size_t V>
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bool solve(int x, int y, int mov, std::array <std::array <int, V>, V> &sol,
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const std::array <int, V> &xmov, std::array <int, V> &ymov) {
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int k, xnext, ynext;
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if (mov == V * V) {
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return true;
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}
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for (k = 0; k < V; k++) {
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xnext = x + xmov[k];
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ynext = y + ymov[k];
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if (backtracking::issafe<V>(xnext, ynext, sol)) {
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sol[xnext][ynext] = mov;
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if (backtracking::solve<V>(xnext, ynext, mov + 1, sol, xmov, ymov) == true) {
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return true;
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}
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else {
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sol[xnext][ynext] = -1;
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}
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}
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}
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return false;
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}
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} // namespace backtracking
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/**
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* Main function
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*/
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int main() {
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const int n = 8;
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std::array <std::array <int, n>, n> sol = { 0 };
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int i, j;
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for (i = 0; i < n; i++) {
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for (j = 0; j < n; j++) { sol[i][j] = -1; }
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}
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std::array <int, n> xmov = { 2, 1, -1, -2, -2, -1, 1, 2 };
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std::array <int, n> ymov = { 1, 2, 2, 1, -1, -2, -2, -1 };
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sol[0][0] = 0;
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bool flag = backtracking::solve<n>(0, 0, 1, sol, xmov, ymov);
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if (flag == false) {
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std::cout << "Error: Solution does not exist\n";
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}
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else {
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for (i = 0; i < n; i++) {
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for (j = 0; j < n; j++) { std::cout << sol[i][j] << " "; }
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std::cout << "\n";
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}
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}
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return 0;
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}
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