Question

C++, 2 dimensional arrays !

So I have to solve this problem: http://screencast.com/t/pj9XALij

That's my code for the problem: http://pastebin.com/f6nVAhPD


I am stuck at part (f) , my results are not giving me the correct answer. Can you please help me find out what I am doing wrong ?

Answer 1

The problem is in how you are finding your fours. For doing this mathematically, you can look into using %.

Or, you could use to_string() and then search the string.

Answer 2

One thing you can do is temporarily turn off the table cout, then turn on something that prints out what you find for fours. You should get smething like:

4
4 14
24
4 24 40
40 45
24 42 48 54
14 42 49
24 40 48 64
45 54
40
Sum of all numbers: 3025
There are 51 numbers that are evenly divisible by 3.
There are 23 numbers that have a 4 in them.

Answer 3

Changed just enough to print what fours you are owingspaning, it is:
http://pastebin.com/YGvZdSAi

Which gets me:
4var 4var 4n 4var 4var 4var 4var 4var 4var 4var 4var 4var 4var
1 2 3 4 5 6 7 8 9 10
2 4 6 8 10 12 14 16 18 20
3 6 9 12 15 18 21 24 27 30
4 8 12 16 20 24 28 32 36 40
5 10 15 20 25 30 35 40 45 50
6 12 18 24 30 36 42 48 54 60
7 14 21 28 35 42 49 56 63 70
8 16 24 32 40 48 56 64 72 80
9 18 27 36 45 54 63 72 81 90
10 20 30 40 50 60 70 80 90 100


Sum : 3025
Divisible : 51
Fours : 13

Answer 4

owingspaning ... ummm.... I am gonna blame that one on the cold medicine!

Makes things more interesting that usual.

I think I meant evaluating.

Also, I now have code that does this:

1 2 3 4 5 6 7 8 9 10
2 4 6 8 10 12 14 16 18 20
3 6 9 12 15 18 21 24 27 30
4 8 12 16 20 24 28 32 36 40
5 10 15 20 25 30 35 40 45 50
6 12 18 24 30 36 42 48 54 60
7 14 21 28 35 42 49 56 63 70
8 16 24 32 40 48 56 64 72 80
9 18 27 36 45 54 63 72 81 90
10 20 30 40 50 60 70 80 90 100
Sum of all numbers: 3025
There are 51 numbers that are evenly divisible by 3.
There are 23 numbers that have a 4 in them.
Sum of row six is: 330
Column sums in the format of <colum#>:<sum>
1:55 2:110 3:165 4:220 5:275 6:330 7:385 8:440 9:495 10:550
Find is a number is in a row.
What ROW to search? 7
What NUMBER to look for? 35
35 is in row 7.
The sum of the upper right to lower left diagonal is: 220
The sum of the upper left to lower right diagonal is: 385

And:
What ROW to search? 7
What NUMBER to look for? 11
11 is not in row 7.

For ones that are not there.

Answer 5

Thanks a lot

Answer 6

Did you work out with % what math you need to do to find things with a 4 in them? One other thing, you need to test 40 to 49 differently than the rest of the numbers in this range if you do it by math.

Answer 7

If you think about it, you find the things dividable by three using var%3=0, right? But what if var%3=1, what would you be finding? Well, all things that when divided by 3 had a remainder of 1. Now, how can use use that basic concept to find things that have a 4 in them? It won't be %3 or %4, but it will be %something.