markzxx/CProgramming-SudokuGenerator

Using C programming to generate Sudoku

SudokuGenerator

A short and simple personal project
Using C programming language to generte simple sudoku puzzle

Click Here to view my program

Getting Started

The main idea of Sudoku generator is to create a good root of a sudoku, and generate different versions of a complete Sudoku by swapping and shuffling rows and columns.

Here is the Result

Details of the Sudoku generator

1. Create the good root of Sudoku in order

     /* Create the root of sudoku */
    for (int countGroup=0; countGroup<3; countGroup++){
        for (int countR=0; countR<3; countR++){
            int pos = countR*3 + countGroup;
            for (int num=1; num<10; num++){
                if (pos == 9) pos-=9;
                sudoku[countR+countGroup*3][pos] = num;
                pos++;
            }
        }
    }

2. Shuffle rows and columns for each group: Randomly pick two rows or columns in same group and swap them.

/* Swapping two rows or columns in the same group */
void shuffleForEachGroup(char* rowOrCol, int ** sudoku){
    for (int i=0; i<3; i++){
        int random = generateRandomeNumer();
        // no swap if zero is generate 
        if (random != 0){
            if (strcmp(rowOrCol, "row") == 0) 
                shuffleTwoRows(sudoku,random, i);
            
            else 
                shuffleTwoCols(sudoku,random, i);   
        }
    }
}

/* Swapping two rows */
void shuffleTwoRows(int ** sudoku, int random, int group){
    int temp;
    int row1 = 3*group, row2 = 3*group+random;
    
    for (int i=0; i<9; i++){
        temp = sudoku[row1][i];
        sudoku[row1][i] = sudoku[row2][i];
        sudoku[row2][i] = temp;
    }       
}

/* Swapping two columns */
void shuffleTwoCols(int ** sudoku, int random, int group){
    int temp;
    int col1 = 3*group, col2 = 3*group+random;
    
    for (int i=0; i<9; i++){
        temp = sudoku[i][col1];
        sudoku[i][col1] = sudoku[i][col2];
        sudoku[i][col2] = temp;
    } 
}
     /* Main Program */
    //Shuffle rows for each group (within the 3×3 borders)
    shuffleForEachGroup("row", sudoku);
    
    //Shuffle columns for each group (within the 3×3 borders)
    shuffleForEachGroup("col", sudoku);

3. Shuffle Two Groups: Randomly pick two groups and swap them in Row or Col.

/* Swapping two groups vertically or horizontally */
void shuffleGroups(char* rowOrCol, int ** sudoku){
    //pick two different groups to swap
    int group1 = generateRandomeNumer(),  group2=group1;
    while(group1 == group2) group2 = generateRandomeNumer();
    group1 *=3, group2 *= 3;
    
    int temp;
    for (int i=0; i<3; i++){
        for (int j=0; j<9; j++){
            if (strcmp(rowOrCol,"row") == 0){
                temp = sudoku[group1+i][j];
                sudoku[group1+i][j] = sudoku[group2+i][j];
                sudoku[group2+i][j] = temp;
            }
            else{
                temp = sudoku[j][group1+i];
                sudoku[j][group1+i] = sudoku[j][group2+i];
                sudoku[j][group2+i] = temp;
            }
        }
    }    
}

     /* Main Program */
    //Shuffle two groups of rows
    shuffleGroups("row", sudoku);
    
    // Shuffle two groups of col
    shuffleGroups("col", sudoku);