C# Problem With Array - Topic

Member

Posts: 2,303

Joined: Oct 11 2007

Gold: 0.00

Mar 21 2014 03:03pm

Hi, I'm currently designing some game and I've got myself to a problem. Let me explain

I'm trying to write down an algorithm which goes from ex1 to ex2 :

Ex1

Code

2 1
1 -1
-1 2
-1 1

Ex2

Code

-1 -1
-1 1
2 1
1 1

So basically, -1 represents an empty space in my game. What I want to happen is some sort of gravity.

Here is my code so far (Not working)

Code

public void applyGravity()
{
for (int i = 0; i < BOARD_WIDTH; i++)
{
for (int j = BOARD_HEIGHT - 1; j > 0; j--)
{
if (grid[i, j] == -1)
{
int cpt = 1;

while (grid[i, j - cpt] == -1)
{
if (cpt < j)
{
cpt++;
}
else
{
break;
}

}

//swap values

grid[i, j - cpt] = grid[i, j];
grid[i, j] = -1;
}
}
}
}

Can someone explain where I go wrong? Thanks

labatymo

Member

Posts: 2,757

Joined: Nov 26 2007

Gold: 1,214.81

Mar 21 2014 04:56pm

there's no pattern between the first and second example...

what are you trying to do exactly?

Eleven11

Member

Posts: 2,303

Joined: Oct 11 2007

Gold: 0.00

Mar 24 2014 12:18pm

Quote (labatymo @ 21 Mar 2014 17:56)

there's no pattern between the first and second example...

what are you trying to do exactly?

All the -1 elements get on top on the array... It represents an empty zone (tile) in my game

Sorry I have mad a mistake in my example :

Code

1 2 1
-1 2 -1
1 -1 -1

should become

Code

-1 -1 -1
1 2 -1
1 2 1

Thanks

This post was edited by Eleven11 on Mar 24 2014 12:22pm

Minkomonster

Member

Posts: 1,995

Joined: Jun 28 2006

Gold: 7.41

Mar 24 2014 05:25pm

So you basically just want to sort a column? Something like this (LOL BubbleSort):

Code

public void applyGravity(int[,] grid)
{
if(grid.GetLength(0) != grid.GetLength(1)) throw new ArgumentException("Must be a NxN matrix");

int len = grid.GetLength(0);

for (int column = 0; column < len; column++)
{
for (int i = 0; i < len - 1; i++)
{
for (int j = i + 1; j < len; j++)
{
if (grid[j, column] == -1)
{
int t = grid[i, column];
grid[i, column] = grid[j, column];
grid[j, column] = t;
}
}
}
}
}

This post was edited by Minkomonster on Mar 24 2014 05:25pm

Azrad

Member

Posts: 10,812

Joined: Oct 15 2009

Gold: Locked

Warn: 20%

Mar 24 2014 05:27pm

Quote (Minkomonster @ Mar 24 2014 04:25pm)

So you basically just want to sort a column? Something like this (LOL BubbleSort):

I somehow don't think that is what he wants, although you are right: that is what is example seems to demand...

carteblanche

Member

Posts: 32,925

Joined: Jul 23 2006

Gold: 3,804.50

Mar 24 2014 05:33pm

Quote (Azrad @ Mar 24 2014 06:27pm)

I somehow don't think that is what he wants, although you are right: that is what is example seems to demand...

No, he doesn't want to sort. he just wants to shift each cell down until -1 are all on top.

ex:
1 2
2 1
-1 -1

would become:

-1 -1
1 2
2 1

just loop from the bottom. if it's -1, copy the value from above down and change the value above to -1. repeat for every row

eg:

Code

for (row = max; row > 0; row--){
if (matrix[col][row] == -1){
matrix[col][row] = matrix[col][row-1];
matrix[col][row-1] = -1;
}
}

can't think right now if it's col, row or vice versa. regardless, this should shift everything down once, or one step of your gravity. you can repeat #rows-1 times if you want to shift until everything's down.

This post was edited by carteblanche on Mar 24 2014 05:36pm

Minkomonster

Member

Posts: 1,995

Joined: Jun 28 2006

Gold: 7.41

Mar 24 2014 05:33pm

Quote (Azrad @ Mar 24 2014 06:27pm)

I somehow don't think that is what he wants, although you are right: that is what is example seems to demand...

He said specifically he wanted all the -1's to be "on top." I can't think of any other way to interpret that /shrug

Perhaps sort was the wrong word? I maintanined the order of the array column. I just shifted all -1's to the top.

This post was edited by Minkomonster on Mar 24 2014 05:34pm

Eleven11

Member

Posts: 2,303

Joined: Oct 11 2007

Gold: 0.00

Mar 24 2014 06:29pm

Done it... I admit i must have been lazy thinking it

Code

for (int j = 0; j < BOARD_WIDTH; j++)
{
for (int i = BOARD_HEIGHT-1/; i > 0; i--)
{

if (grid[i, j] == -1)
{

int cpt = 1;

while (grid[i - cpt, j] == -1)
{
if (cpt < i)
{
cpt++;
}
else
{
break;
}
}
grid[i, j] = grid[i - cpt, j];
grid[i - cpt, j] = -1;

}
}
}

e/ Yet I dont want to base myself on the numbers themselves because I dont know if I will have an element of the -2 value in the future

This post was edited by Eleven11 on Mar 24 2014 06:31pm

Go Back To Programming & Development Topic List