## Build a maze programmatically in Excel

The image above shows the creation of a maze located on a worksheet. A macro builds this maze randomly, a new version is generated each time you start the macro.

Two weeks ago I posted a link to a workbook containing formulas calculating the shortest path in a maze. Today I have created a macro that builds a random maze.

The cell grid is 110 x 110 and the start cell is randomly chosen and colored yellow. The macro then randomly creates a path until it can´t move further. The endpoint is a cell with the longest distance to the start cell, colored blue.

The path between them is usually around 2500 cells. You can find the blue cell somewhere in the upper left corner, at the end of the animation. There is only one possible path between the start cell and end cell.

The animated image below shows the macro creating the maze, you can see how the macro creates new paths when there is nowhere to go.

To start building a new maze press with left mouse button on the button to the right of the maze, on the worksheet.

### Change animation speed

You can change the speed of this by changing this line in the macro:

If (k / 100) - Int(k / 100) = 0 Then

If you want it really slow, change it to:

If (k / 1) - Int(k / 1) = 0 Then

If you want it faster, change it to:

If (k / 200) - Int(k / 200) = 0 Then

### Count distance between start cell and end cell

Add this line:

MsgBox Tcount

before End Sub

### VBA Code

'Name macro Sub BuildMaze() 'Disable screen refresh Application.ScreenUpdating = False 'Dimension variables and declare data types 'Array variable loc keeps track of the maze in creation Dim loc(0 To 110, 0 To 110) 'Array variable path keeps track of places to go not visited earlier Dim path(0 To 3) 'The visloc array variable keeps track of the current coordinate Dim visloc() As Variant 'Redimension array making it a dynamic array ReDim visloc(1, 0) 'Save value 1 to each cell in cell range B2:DG111 Range("B2:DG111") = 1 'Create a random value between 1 and 108 and save it ti variables StartR and StartC StartR = Int(Rnd * 108) + 1 StartC = Int(Rnd * 108) + 1 'Save text value S to a cell in cell range B2:DG111 based on random values stored in variables StartR and StartC Range("B2:DG111").Cells(StartR, StartC) = "S" 'Save number 1 to array variable loc based on random values stored in variables StartR and StartC loc(StartR, StartC) = 1 'Save random values stored in variables StartR and StartC to array variable visloc row 0 (zero), column 0 (zero) and row 1 and column 0 (zero) visloc(0, 0) = StartR visloc(1, 0) = StartC 'Do ... Loop statement until a condition is met meaning the lines between Do and Loop until will be rund repeatedly until the condition is met Do 'Save 0 (zero) to variable c c = 0 'For ... Next statement repeats line(s) between For and Next 4 times (0, 1, 2, 3) For i = 0 To 3 'Save zero to array variable path based on variable i path(i) = 0 Next i 'If ... then statement runs lines between If and End If if a condition is met If visloc(0, UBound(visloc, 2)) - 2 >= 1 Then 'If ... then statement runs lines between If and End If if the conditions are met If loc(visloc(0, UBound(visloc, 2)) - 1, visloc(1, UBound(visloc, 2))) <> 1 And _ loc(visloc(0, UBound(visloc, 2)) - 2, visloc(1, UBound(visloc, 2))) <> 1 And _ loc(visloc(0, UBound(visloc, 2)) - 1, visloc(1, UBound(visloc, 2)) + 1) <> 1 And _ loc(visloc(0, UBound(visloc, 2)) - 1, visloc(1, UBound(visloc, 2)) - 1) <> 1 Then 'Save number 1 to array variable path position 0 path(0) = 1 'Save number 1 to variable c c = 1 End If End If 'If ... then statement runs lines between If and End If if a condition is met If visloc(0, UBound(visloc, 2)) + 2 <= 110 Then 'If ... then statement runs lines between If and End If if the conditions are met If loc(visloc(0, UBound(visloc, 2)) + 1, visloc(1, UBound(visloc, 2))) <> 1 And _ loc(visloc(0, UBound(visloc, 2)) + 2, visloc(1, UBound(visloc, 2))) <> 1 And _ loc(visloc(0, UBound(visloc, 2)) + 1, visloc(1, UBound(visloc, 2)) + 1) <> 1 And _ loc(visloc(0, UBound(visloc, 2)) + 1, visloc(1, UBound(visloc, 2)) - 1) <> 1 Then 'Save number 1 to variable c c = 1 'Save number 1 to array variable path position 1 path(1) = 1 End If End If 'If ... then statement runs lines between If and End If if a condition is met If visloc(1, UBound(visloc, 2)) - 2 >= 1 Then 'If ... then statement runs lines between If and End If if the conditions are met If loc(visloc(0, UBound(visloc, 2)), visloc(1, UBound(visloc, 2)) - 1) <> 1 And _ loc(visloc(0, UBound(visloc, 2)), visloc(1, UBound(visloc, 2)) - 2) <> 1 And _ loc(visloc(0, UBound(visloc, 2)) + 1, visloc(1, UBound(visloc, 2)) - 1) <> 1 And _ loc(visloc(0, UBound(visloc, 2)) - 1, visloc(1, UBound(visloc, 2)) - 1) <> 1 Then 'Save number 1 to variable c c = 1 'Save number 1 to array variable path position 2 path(2) = 1 End If End If 'If ... then statement runs lines between If and End If if a condition is met If visloc(1, UBound(visloc, 2)) + 2 <= 110 Then 'If ... then statement runs lines between If and End If if the conditions are met If loc(visloc(0, UBound(visloc, 2)), visloc(1, UBound(visloc, 2)) + 1) <> 1 And _ loc(visloc(0, UBound(visloc, 2)), visloc(1, UBound(visloc, 2)) + 2) <> 1 And _ loc(visloc(0, UBound(visloc, 2)) + 1, visloc(1, UBound(visloc, 2)) + 1) <> 1 And _ loc(visloc(0, UBound(visloc, 2)) - 1, visloc(1, UBound(visloc, 2)) + 1) <> 1 Then 'Save number 1 to variable c c = 1 'Save number 1 to array variable path position 3 path(3) = 1 End If End If 'Check if variable c is equal to 0 (zero) If c = 0 Then 'Check if number saved in variable Ccount is larger than number stored in variable Tcount If Ccount > Tcount Then 'Save number stored in variable Ccount to variable Tcount Tcount = Ccount 'Save number stored in array variable visloc in position row 0 and column UBound(visloc, 2) Er = visloc(0, UBound(visloc, 2)) 'Save number stored in array variable visloc in position row 1 and column UBound(visloc, 2) Ec = visloc(1, UBound(visloc, 2)) End If 'Subtract number stored in variable Ccount with 1 Ccount = Ccount - 1 'Redimension array variable visloc ReDim Preserve visloc(UBound(visloc, 1), UBound(visloc, 2) - 1) 'Continue here if variable c is not equal to 0 (zero) Else 'Save 0 (zero) to variable c c = 0 'Keep iterating until c is not equal to 0 (zero) Do Until c <> 0 'Create a random integer between 0 and 4 rrand = Int(Rnd * 4) 'Check if number stored in array variable path position based on number in variable rrand is equal to 1 'If True then save number stored in variable rrand plus 1 to variable c If path(rrand) = 1 Then c = rrand + 1 Loop 'Redimension array variable visloc but keep previous values ReDim Preserve visloc(UBound(visloc, 1), UBound(visloc, 2) + 1) 'Select case statement. Based on what variable c contains case 1 to 4 is rund Select Case c 'If variable c is equal to 1 Case 1 visloc(0, UBound(visloc, 2)) = visloc(0, UBound(visloc, 2) - 1) - 1 visloc(1, UBound(visloc, 2)) = visloc(1, UBound(visloc, 2) - 1) 'If variable c is equal to 2 Case 2 visloc(0, UBound(visloc, 2)) = visloc(0, UBound(visloc, 2) - 1) + 1 visloc(1, UBound(visloc, 2)) = visloc(1, UBound(visloc, 2) - 1) 'If variable c is equal to 3 Case 3 visloc(0, UBound(visloc, 2)) = visloc(0, UBound(visloc, 2) - 1) visloc(1, UBound(visloc, 2)) = visloc(1, UBound(visloc, 2) - 1) - 1 'If variable c is equal to 4 Case 4 visloc(0, UBound(visloc, 2)) = visloc(0, UBound(visloc, 2) - 1) visloc(1, UBound(visloc, 2)) = visloc(1, UBound(visloc, 2) - 1) + 1 End Select 'Add 1 to number stored in variable Ccount Ccount = Ccount + 1 'Clear values in cell range B2:DG111 Range("B2:DG111").Cells(visloc(0, UBound(visloc, 2)), visloc(1, UBound(visloc, 2))) = "" 'Save number 1 to array variable visloc loc(visloc(0, UBound(visloc, 2)), visloc(1, UBound(visloc, 2))) = 1 'Apply changes DoEvents End If 'Add 1 to variable k k = k + 1 'If k is 50, 100, 150 and so on ... If (k / 50) - Int(k / 50) = 0 Then 'Show changes on screen Application.ScreenUpdating = True 'Hide changes on screen Application.ScreenUpdating = False End If 'Loop until array variable visloc is equal to start coordinates meaning the maze is complete Loop Until visloc(0, UBound(visloc, 2)) = StartR And visloc(1, UBound(visloc, 2)) = StartC 'Show changes on screen Application.ScreenUpdating = True 'Save text value B to cell in cell range B2:DG111 based on coordinates in variable Er and Ec Range("B2:DG111").Cells(Er, Ec) = "B" End Sub

### Where to put the code?

- Press shortcut keys Alt + F11 to open the Visual Basic Editor (VB Editor).
- Press with left mouse button on "Insert" on the top menu, see image above.
- Press with mouse on "Module" to create a module in your workbook. The image above shows the module named Module1 in the Project Explorer window.
- Copy and paste VBA code to the module which is also shown in the image above.
- Exit the VB Editor and return to Excel.

Terry wants to make a different sized maze and I think that is a great idea. Perhaps you remember that I […]

### 10 Responses to “Build a maze programmatically in Excel”

### Leave a Reply to Customize excel maze | Get Digital Help - Microsoft Excel resource

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So how do we combine our two projects? :)

https://optionexplicitvba.com/2013/09/21/excel-3d-maze-update/

Jordan Goldmeier,

Great looking project but I can´t open the file: maze-example.xlsm

What am I doing wrong?

Really? Let me take a look at that.

Very beautiful

This is cool.

I'm going to try to decipher this and make a different sized maze (maybe even variable) ... unless you think it would make a good project and blog post for you (hint :)).

Either way, thanks.

[…] Terry wants to make a different sized maze and I think that is a great idea. Perhaps you remember that I built a maze in excel last week, if you don´t check it out. […]

Hi Oscar ,

Is it possible to create the maze so that both the entry and the exit are on the sides of the maze ? At present the end of the maze is in the middle of the maze.

Narayan

[…] Build a maze […]

my excel just comes up with random cells filled with 1

Wow! That was AWESOME! I was wondering if there was a way to do this using just the borders in the cells, like a ''traditional'' maze. Thanks!