Sudoku example fix #1287
Sudoku example fix #1287
Conversation
**Problem**
the logic behind `countDuplicates` is invalid because it's doing this:
(incorrect)
```
if(duplicates + e11 == e21)
duplicates = 1;
else
duplicates = 0;
```
Instead of this:
(correct)
```
if(e11 == e21)
duplicates = duplicates + 1;
else
duplicates = duplicates;
```
**Solution**
I'm using an auxiliary variable to fix this
**Alternative solution**
We can also fix it with an array and a loop. But I went for the auxiliary variable for no particular reason.
```
def countDuplicates(field e11, field e12, field e21, field e22) -> u32 {
u32[6] mut duplicates = [0,0,0,0,0,0];
duplicates[0] = e11 == e12 ? 1 : 0;
duplicates[1] = e11 == e21 ? 1 : 0;
duplicates[2] = e11 == e22 ? 1 : 0;
duplicates[3] = e12 == e21 ? 1 : 0;
duplicates[4] = e12 == e22 ? 1 : 0;
duplicates[5] = e21 == e22 ? 1 : 0;
u32 mut count = 0;
for u32 i in 0..5 {
count = count + duplicates[i];
}
return count;
}
```
And btw, I also added an assert to make sure we check for this validation. I've tested this on the playground and on chain on goerli and with this changes it works correctly.
|
Oh good catch, seems like a precedence issue, would a smaller change like the following work? - duplicates = duplicates + e11 == e21 ? 1 : 0;
+ duplicates = duplicates + (e11 == e21 ? 1 : 0); |
| @@ -74,5 +81,6 @@ def main(field a21, field b11, field b22, field c11, field c22, field d21, priva | |||
| duplicates = duplicates + countDuplicates(b12, b22, d12, d22); | |||
|
|
|||
| // the solution is correct if and only if there are no duplicates | |||
| assert(duplicates == 0); | |||
There was a problem hiding this comment.
This is fine but then let's return nothing
|
The smaller change worked! I tested it on the playground and works well 👍 |
|
Woops, closed this by accident. Just reopened |
|
After further thought, I went back returning a bool instead of nothing. I think it makes more sense. Specially for newcomers like myself. |
|
Hey guys, I wanted to know if you guys think something else should be done on this PR. I would greatly appreciate if we merge this because I'm doing educational content and it would be nice to point to this official repo instead of my own. |
|
Yes we can merge it soon. Can you please just add a changelog at |
|
Added the changelog @Schaeff |
The problem
the logic behind
countDuplicatesis invalid because it's doing this:(incorrect)
Instead of this:
(correct)
The solution
I'm using an auxiliary variable to fix this
Alternative solution
We can also fix it with an array and a loop. But I went for the auxiliary variable for no particular reason.
And btw, I also added an assert to make sure we check for this validation. I've tested this on the playground and on chain on goerli and with this changes it works correctly.
Thanks for putting adding the examples. It has helped me a lot.
Cheers!