Determine if set of connected tiles can fit inside grid

Question

Feel free to edit the title; I had a hard time figuring out how to explain it in a single line.

Here goes. I'm trying to generate these grids automatically, and randomly.

I have a grid of 25 tiles (indicated by #)

#####
#####
#####
#####

Let's say that I have 2 monsters I want to place in this grid, each monster occupies 3 or 4 tiles, with different patterns (these are not random, but is defined somewhere).

Monster 1 indicated by the letter A Monster 2 indicated by the letter B

An example of this:

#AA##
#BA##
#BBB#
#####

Or it could be (this is whre the randomness comes in):

AA###
#A###
#B###
#BBB#

How would I go about calculating where, for example, monster B fits in the grid after A has been placde? Monster B has a pattern of:

B
BBB

And A has a pattern of:

AA
 A

A possible pattern could also be (for a different monster than A and B):

C
 C
  C

Is this even possible to automate? Hope that makes sense, otherwise I can try drawing it instead.

Thanks

Answer 1

The best way to do this would be to randomly pick a tile, and just do checks for the other tiles needed to place the monster. If the monster can't fit being placed in the tile given, then loop until a spot is found where it can fit.

int[,] monsterA = [[1,1]
                  [0,1]]

int[,] level = [[0,0,0]
                [0,0,0]
                [0,0,0]]

point placeLocation(int[,] layout, int[,] monster)
{
    bool completed = false

    point chosenPoint

    while (completed == false}  //while a good spot hasn't been found
    {
        //method which picks a random point from the array
        chosenPoint = getRandomPoint(layout)

        bool fail = false
        for (int i = 0;i<monster.width;i++)  
        {
            for (int j=0; j<monster.height;j++)
            {
                if (monsterA[i,j] == 1 && level[chosenPoint.X + i,chosenPoint.Y + j] != 0
                {

                   //if any point of the monster is blocked, fail is set to true
                   fail = true;
                }
            }
        }
        if (fail == false){
           //monster can fit here
           completed = true
        }
    }
    return chosenPoint
}

If you want to prevent the loop from running forever, you could put a limited number of tries on it or keep track of chosen points until all of them have been exhausted.