88 lines
1.9 KiB
C
88 lines
1.9 KiB
C
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#include <stdio.h>
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#include <stdlib.h>
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typedef char Sudoku[81];
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typedef enum { true, false } bool;
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bool* get_possible_solutions(Sudoku s, int row, int col) {
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bool* solutions = malloc(sizeof(bool)*10);
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for(int i = 0; i < 10; i++) solutions[i] = true;
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for(int ccol = 0; ccol < 9; ccol++)
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solutions[ s[row*9+ccol] ] = false;
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for(int crow = 0; crow < 9; crow++)
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solutions[ s[crow*9+col] ] = false;
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for(int crow = row - row%3, rsteps = 0; rsteps < 3; crow++, rsteps++) {
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for(int ccol = col - col%3, csteps = 0; csteps < 3; ccol++, csteps++) {
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solutions[ s[crow*9 + ccol] ] = false;
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}
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}
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return solutions;
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}
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int sudoku_solve_rec(Sudoku s, int row, int col) {
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if(row >= 9)
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return 1;
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if(col >= 9)
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return sudoku_solve_rec(s, row + 1, 0);
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if(s[row*9+col] != 0)
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return sudoku_solve_rec(s, row, col + 1);
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bool* solutions = get_possible_solutions(s, row, col);
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for(int solution = 1; solution <= 9; solution++) {
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if(solutions[solution] == false) continue;
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s[row*9+col] = solution;
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if(sudoku_solve_rec(s, row, col + 1)) {
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free(solutions);
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return 1;
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}
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}
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s[row*9+col] = 0;
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free(solutions);
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return 0;
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}
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int sudoku_solve(Sudoku s) {
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return sudoku_solve_rec(s, 0,0);
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}
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int main( int argc, char *argv[] ) {
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Sudoku s = {
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0,3,0,0,0,0,0,0,0,
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0,0,0,1,9,5,0,0,0,
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0,0,8,0,0,0,0,6,0,
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8,0,0,0,6,0,0,0,0,
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4,0,0,8,0,0,0,0,1,
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0,0,0,0,2,0,0,0,0,
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0,6,0,0,0,0,2,8,0,
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0,0,0,4,1,9,0,0,5,
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0,0,0,0,0,0,0,7,0
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};
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if(sudoku_solve(s)) {
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printf("Solved\n");
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} else {
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printf("Not solved\n");
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}
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for(int row = 0; row < 9; row++) {
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for(int col = 0; col < 9; col++) {
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printf("%d ",s[row*9+col]);
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}
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printf("\n");
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}
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return 0;
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}
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