Transform for loop into while loop

emayu (1)
Hello!
I am trying to resolve a sudoku and i have got this code that is working well.
I would like to transform all the for loop into a while loop, I'm trying for hours now and it can't work.

Here is the original program : 

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#include <stdio.h>

#define SIZE 9

int matrix[9][9] = {
    {8,0,0,0,0,0,0,0,0},
    {0,0,3,6,0,0,0,0,0},
    {0,7,0,0,9,0,2,0,0},
    {0,5,0,0,0,7,0,0,0},
    {0,0,0,0,4,5,7,0,0},
    {0,0,0,1,0,0,0,3,0},
    {0,0,1,0,0,0,0,6,8},
    {0,0,8,5,0,0,0,1,0},
    {0,9,0,0,0,0,4,0,0}
};

void print_sudoku()
{
    int i,j;
    for(i=0;i<SIZE;i++)
    {
        for(j=0;j<SIZE;j++)
        {
            printf("%d\t",matrix[i][j]);
        }
        printf("\n\n");
    }
}

int number_unassigned(int *row, int *col)
{
    int num_unassign = 0;
    int i,j;
    for(i=0;i<SIZE;i++)
    {
        for(j=0;j<SIZE;j++)
        {
            if(matrix[i][j] == 0)
            {
                *row = i;
                *col = j;
                num_unassign = 1;
                return num_unassign;
            }
        }
    }
    return num_unassign;
}
int is_safe(int n, int r, int c)
{
    int i,j;
    for(i=0;i<SIZE;i++)
    {
        if(matrix[r][i] == n)
            return 0;
    }
    for(i=0;i<SIZE;i++)
    {
        if(matrix[i][c] == n)
            return 0;
    }
    int row_start = (r/3)*3;
    int col_start = (c/3)*3;
    for(i=row_start;i<row_start+3;i++)
    {
        for(j=col_start;j<col_start+3;j++)
        {
            if(matrix[i][j]==n)
                return 0;
        }
    }
    return 1;
}
int solve_sudoku()
{
    int row;
    int col;
    if(number_unassigned(&row, &col) == 0)
        return 1;
    int n,i;
    for(i=1;i<=SIZE;i++)
    {
        if(is_safe(i, row, col))
        {
            matrix[row][col] = i;
            if(solve_sudoku())
                return 1;
            matrix[row][col]=0;
        }
    }
    return 0;
}

int main()
{
    if (solve_sudoku())
        print_sudoku();
    else
        printf("Error\n");
    return 0;
}







and here is what I tried but that is not working : 

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#include <stdio.h>
#define SIZE 9

int matrix[9][9] = {
    {8,0,0,0,0,0,0,0,0},
    {0,0,3,6,0,0,0,0,0},
    {0,7,0,0,9,0,2,0,0},
    {0,5,0,0,0,7,0,0,0},
    {0,0,0,0,4,5,7,0,0},
    {0,0,0,1,0,0,0,3,0},
    {0,0,1,0,0,0,0,6,8},
    {0,0,8,5,0,0,0,1,0},
    {0,9,0,0,0,0,4,0,0}
};

void print_sudoku()
{
    int i;
    int j;
    
    i = 0;
    while(i < SIZE)
    {
        i++;
        j = 0;
        while(j < SIZE)
        {
            j++;
            printf("%d\t",matrix[i][j]);
        }
        printf("\n\n");
    }
}

int number_unassigned(int *row, int *col)
{
    int num_unassign = 0;
    int i,j;
    for(i=0;i<SIZE;i++)
    {
        for(j=0;j<SIZE;j++)
        {
            if(matrix[i][j] == 0)
            {
                *row = i;
                *col = j;
                num_unassign = 1;
                return num_unassign;
            }
        }
    }
    return num_unassign;
}


int is_safe(int n, int r, int c)
{
    int i;
    int j;
    
    i = 0;
    while(i < SIZE)
    {
        
        if(matrix[r][i] == n)
        i++;
            return 0;
    }
    i = 0;
    while(i < SIZE)
    {
        i++;
        if(matrix[i][c] == n)
            return 0;
    }
    int row_start;
    i = row_start;
    row_start = (r/3)*3;
    
    row_start = (c/3)*3;
    
    while(i < row_start + 3)
    {
        i++;
        int col_start;
        j = col_start;
        while(j<col_start + 3)
        {
            j++;
            if(matrix[i][j]==n)
                return 0;
        }
    }
    return 1;
}  

int solve_sudoku()
{
    int row;
    int col;
    int i;
    int n;
    i = 1;
    
    if (number_unassigned(&row, &col) == 0)
        return 1;
    while (i <= SIZE)
    {
        i++;
        if (is_safe(i, row, col))
        {
            matrix[row][col] = i;
            if(solve_sudoku())
                return (1);
                
            matrix[row][col] = 0;
        }
    }
    return (0);
}


int main()
{
    if (solve_sudoku())
        print_sudoku();
    else
        printf("erreur\n");
    return 0;
}



could you help me?
Thank you very much !
Last edited on
helios (17574)
I would like to transform all the for loop into a while loop
Why?
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