Originally posted by: AdamGregory

Hey there,

I'm trying to determine how many times a particular number appears in an array of ranges defined by start values and end values.

My current approach is to iterate over the array of ranges and convert from a range to an array using:
all (j in rangeStart..rangeEnd) j
Where rangeStart and rangeEnd are both decision variables, and sum up or count the number of occurrences of a particular value.

The issue is that the generated array does not appear to contain any of the values on the range rangeStart..rangeEnd if either rangeStart or rangeEnd is a decision variable. If put placeholder integers in their place, the array appears correctly.

Can anyone advise on this particular problem or suggest an alternative approach to count the number of occurrences of a particular value in an array of ranges?

Thanks

Hi,

if you use CPO, have you tried count ?

Example

using CP;

range R = 1..10;

dvar int+ x[R] in R;

subject to {

  
count(all(i in R) x[i], 2) == 10;

}

regards

Originally posted by: AdamGregory

Thanks for your response.
This is the exact problem I'm having.

using CP;
int findValue = 5;

subject to {
sum (t in Tasks) count(all (j in taskStart[t]..taskEnd[t]) j, findValue) <= 3;
}

The issue is that this constraint doesn't seem to work. The solver selects a solution for which this constraint is not satisfied.
I believe that the section:
all (j in taskStart[t]..taskEnd[t]) j
is not correctly creating an array which contains all the values in the specified range and therefore the occurrences of findValue are not correctly counted.
If I use ints for the endpoints of my range rather than dvar ints the array correctly contains the expected values and the count works as expected.

Hi,

could

using CP;

dvar int x[1..10] in 1..10;
dvar int a in 1..10;
dvar int b in 1..10;

subject to
{
forall(i in 1..10) x[i]==1+i mod 3;
2==sum(i in 1..10)  ((x[i]==2) && (a<=i) && (i<=b));
}

help ?