How is this "number square" problem done with a modulus operator?-CodePudding

I have come across a very familiar problem doing some exercises and for the life of me cannot figure it out using the intended method -- the modulus % operator -- that accepts (int min, int max) parameters as beginning and end limits.

It is to print the following with a call of numberSquare(1, 5):

I have gotten it to work by essentially creating a manual tracker, though I know this is not the correct approach:

private static void numberSquare(int min, int max)
{   
    int difference = max - min;
    // outside loop
    for(int row = min; row <= max; row  )
    {
        // inside loop
        for(int col = row; col <= row   difference; col  )
        {   
            // is in bounds
            if(col <= max)
                System.out.print(col);
            // not in bounds
            else
                System.out.print(col - difference - 1);
        } // next line
        System.out.println();
    }
}

And my other approach using the operator had the inner loop looking like this:

// is in bounds
if(col <= max)
    System.out.print(col);
// not in bounds
else
    System.out.print(col % max   min);

Which gives me an output of:

|12345|                  |12345|
|23452|                  |23451|
|34523|    instead of    |34512|
|45234|                  |45123|
|52345|                  |51234|

I am really struggling to see how I can do this with the modulus % operator and would love any help/suggestions.

Edit for additional information

I got another version to work, but this one also does not have the % operator...

private static void numberSquare(int min, int max)
{
    // track outside rows
    for(int row = min ; row <= max; row  )
    {
       // track inside columns and the print value
       for(int col = min, value = row; 
               col <= max; col  , value  )
       {
           // reset if the value is too high
           value = (value > max) ? min : value;
           System.out.print(value);
       } 
       // next line
       System.out.println();
    } 
}

CodePudding user response：

Assuming your integer is abcd where each letter is a digit. You can do left cyclic shift by first separating bcd and a

bcd = abcd % 1000
a = abcd / 1000 (integer division)

Then, to construct the left cyclic shift from bcd and a

bcda = bcd * 10   a

In Java, this is how I would implement it

void numSquare(int min, int max) {
    int number = 0;
    int div = 1;
    // construct the integer, e.g., 12345, and the corresponding power of tens
    for (int i = max; i >= min; --i) {
        number  = i * div;
        div *= 10;
    }
    div /= 10;
    
    // left cyclic shifting the integer and printing
    int nShifts = max - min   1;
    for (int i = 0; i < nShifts;   i) {
        System.out.println(number);
        number = (number % div) * 10   (number / div);
    }
}

CodePudding user response：

You can calculate the value as (row col - 2) % max 1