Reading a File into a 2D Array - Getting ArrayIndexOutOfBoundsException()
 CodeGuru Home VC++ / MFC / C++ .NET / C# Visual Basic VB Forums Developer.com

# Thread: Reading a File into a 2D Array - Getting ArrayIndexOutOfBoundsException()

1. Junior Member
Join Date
Jan 2012
Posts
17

## Reading a File into a 2D Array - Getting ArrayIndexOutOfBoundsException()

Hi I've been doing Project Euler problems lately but I'm having trouble with Problem 18, here it is:

By starting at the top of the triangle below and moving to adjacent numbers on the row below, the maximum total from top to bottom is 23.

3
7 4
2 4 6
8 5 9 3

That is, 3 + 7 + 4 + 9 = 23.

Find the maximum total from top to bottom of the triangle below:

75
95 64
17 47 82
18 35 87 10
20 04 82 47 65
19 01 23 75 03 34
88 02 77 73 07 63 67
99 65 04 28 06 16 70 92
41 41 26 56 83 40 80 70 33
41 48 72 33 47 32 37 16 94 29
53 71 44 65 25 43 91 52 97 51 14
70 11 33 28 77 73 17 78 39 68 17 57
91 71 52 38 17 14 91 43 58 50 27 29 48
63 66 04 68 89 53 67 30 73 16 69 87 40 31
04 62 98 27 23 09 70 98 73 93 38 53 60 04 23

NOTE: As there are only 16384 routes, it is possible to solve this problem by trying every route. However, Problem 67, is the same challenge with a triangle containing one-hundred rows; it cannot be solved by brute force, and requires a clever method! ;o)

My algorithm for finding the max total is correct. I tested it by manually entering the numbers in a 2d array and the program ran fine. The reason I don't want to do it that way is as this Problem says Problem 67 is the same except much larger numbers and I don't want to be typing numbers all day and also I want to practice manipulating files etc.

Anyway to the point I suppose the best thing I can do really is show you my code and the errors I'm getting. I did some debugging but I can't seem to figure out why the problem is occurring. When I run the program it gives an ArrayIndexOutOfBoundsException(). The .txt file consists of the large group of numbers in the problem description above.

Code:
public class Problem18 {

public static void main(String[] args) throws Exception
{
Problem18 p18 = new Problem18() ;
p18.maxTotalPath() ;
}

{

Scanner scan = new Scanner(file) ;

int[][] triangle = new int[15][15] ;
int m = 0, n = 0 ;
String line ;
while(scan.hasNext())
{
line = scan.nextLine() ;
String[] numbers = line.split(" ") ;

for(int i = 0 ; i < numbers.length ; i++)
{
triangle[m][n] = Integer.parseInt(numbers[i]) ;
//System.out.print(triangle[m][n] + " ") ;
n += 1 ;
}
n = 0 ;
// System.out.println("") ;
m += 1 ;
}
scan.close() ;
return triangle ;
}

public void maxTotalPath() throws Exception
{
for (int i = arr.length - 2 ; i >= 0 ; i--)
{
for (int j = 0 ; j < arr[i].length; j++)
{
arr[i][j] += Math.max(arr[i + 1][j], arr[i + 1][j + 1]);
}
}
System.out.println(Integer.toString(arr[0][0])) ;
}
}
The errors then are:

Code:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 15
at com.jconnolly.projeuler.problems.Problem18.maxTotalPath(Problem18.java:83)
at com.jconnolly.projeuler.problems.Problem18.main(Problem18.java:44)
Any help would be much appreciated thanks!
Last edited by Schonge; July 31st, 2013 at 03:17 PM.

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•