Modify the car sequencing problem. Assume that you have 20 cars to paint in 4 available colors: green, yellow, blue, and white. Due to technical limitations on the assembly line, no more than 6 cars can be painted green, exactly 5 cars must be painted yellow, no more than 7 cars can be painted blue, and no less than 5 cars and no more than 12 cars can be painted white. The first car off the assembly line cannot be painted green.

Suggested Answer

The code that has changed from carseq_basic.cpp follows. You can view the complete program online in the file YourSolverHome/examples/src/carseq_basic_ex3.cpp.

Add the fourth color to the array Names:

const char* Names[] = {"green", "yellow", "blue", "white"};

The following code changes the number of cars and colors:

    const IloInt nbCars    = 20;
    const IloInt nbColors = 4;

You modify the distribute constraint:

    IloIntArray colors(env, 4, 0, 1, 2, 3);
    IloIntVarArray cards(env, nbColors);
    cards[0] = IloIntVar(env, 0, 6);
    cards[1] = IloIntVar(env, 5, 5);
    cards[2] = IloIntVar(env, 0, 7);
    cards[3] = IloIntVar(env, 5, 12);

You should get the following results, though the information displayed by IloSolver::printInformation will vary depending on platform, machine, configuration, and so on.

Feasible Solution
Car 1 color:     yellow
Car 2 color:     green
Car 3 color:     green
Car 4 color:     green
Car 5 color:     green
Car 6 color:     green
Car 7 color:     green
Car 8 color:     yellow
Car 9 color:     yellow
Car 10 color:     yellow
Car 11 color:     yellow
Car 12 color:     blue
Car 13 color:     blue
Car 14 color:     blue
Car 15 color:     blue
Car 16 color:     white
Car 17 color:     white
Car 18 color:     white
Car 19 color:     white
Car 20 color:     white
Number of fails               : 0
Number of choice points       : 15
Number of variables           : 25
Number of constraints         : 2
Reversible stack (bytes)      : 4044
Solver heap (bytes)           : 12084
Solver global heap (bytes)    : 4044
And stack (bytes)             : 4044
Or stack (bytes)              : 4044
Search Stack (bytes)          : 4044
Constraint queue (bytes)      : 11152
Total memory used (bytes)     : 43456
Elapsed time since creation   : 0.16