104 lines
2.6 KiB
C++
104 lines
2.6 KiB
C++
#include <iostream>
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#include <list>
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#include <chrono>
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#include <algorithm>
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#define BOARD_SIZE 81
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#define BOARD_DIMENSION 9
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class Sudoku {
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private:
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int board[BOARD_SIZE];
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public:
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Sudoku(std::string s) {
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for (unsigned int i = 0; i < s.length(); i++) {
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board[i] = (int) (s[i] - '0');
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}
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}
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void solve() {
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// Very naive first attempt: Fails because it sets stuff wrongly and doesn't backtrack
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for (int y = 0; y < BOARD_DIMENSION; y++) {
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for (int x = 0; x < BOARD_DIMENSION; x++) {
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if (get(x, y) == 0) {
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auto possibilities = get_possibilities(x, y);
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set(x, y, possibilities.front());
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}
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}
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}
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// Real search:
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// 1. Sort possibilities by how many new constraints they create
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// 2. Start with the one creating the smallest amount of new constraints
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// 3. Continue until dead end
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// 4. If dead end: Try the next one
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}
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int coordinates_to_id(int x, int y) {
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return y * BOARD_DIMENSION + x;
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}
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int get(int x, int y) {
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return board[coordinates_to_id(x, y)];
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}
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void set(int x, int y, int value) {
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board[coordinates_to_id(x, y)] = value;
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}
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std::list<int> get_possibilities(int x, int y) {
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std::list<int> possibilities{1, 2, 3, 4, 5, 6, 7, 8 ,9};
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// Remove all from this row
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for (int dx = 0; dx < BOARD_DIMENSION; dx++) {
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possibilities.remove(get(dx, y));
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}
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// Remove all from this column
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for (int dy = 0; dy < BOARD_DIMENSION; dy++) {
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possibilities.remove(get(x, dy));
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}
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// Remove all from this quadrant
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for (int dy = 0; dy < 3; dy++) {
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for (int dx = 0; dx < 3; dx++) {
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possibilities.remove(get((x - x % 3) + dx, (y - y % 3) + dy));
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}
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}
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return possibilities;
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}
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void print_board() {
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std::cout << board[0] << " ";
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for (unsigned int i = 1; i < BOARD_SIZE; i++) {
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if (i % 3 == 0 && i % 9 != 0) {
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std::cout << "| ";
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}
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if (i % 9 == 0) {
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std::cout << std::endl;
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}
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if (i % 27 == 0) {
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std::cout << "------+-------+------" << std::endl;
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}
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std::cout << board[i] << " ";
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}
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std::cout << std::endl;
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}
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};
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int main() {
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//char str[82];
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//cin >> str;
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//Sudoku solver(str);
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Sudoku solver("006001849030000000000020006000400320400003000600008000010060003000005004029074005");
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//Sudoku solver("850002400720000009004000000000107002305000900040000000000080070017000000000036040");
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solver.solve();
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solver.print_board();
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return 0;
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} |