chocoteam/choco-solver

package choco;

import org.chocosolver.gui.GUI;
import org.chocosolver.solver.Model;
import org.chocosolver.solver.Solution;
import org.chocosolver.solver.Solver;
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.solver.constraints.Constraint;

import java.util.Arrays;
import java.util.Random;

public class PredictStaffingLevel2 {
public void modelAndSolve(){

    int numOfNurses = 6, numOfDays = 8;
    int numOfTimePeriods = 6, maxNumOfEEs = 15;

    Model model = new Model("Determine Min Staffing Level");
    IntVar[]shifts = model.intVarArray(numOfTimePeriods, 0, maxNumOfEEs);

    // Shifts
    // 12AM-8AM 5
    // 4AM-12PM 2
    // 8AM-4PM 13
    // 12PM-8PM 0
    // 4PM-12AM 12
    // 8PM-4AM 0
    int[] timePeriodStaffingLevels = new int[] {
        5,    // 12AM-4AM 
        7,    // 4AM-8AM  
        15,    // 8AM-12PM 
        8,    // 12PM-4PM
        12, // 4PM-8PM
        9,     // 8PM-12AM
    };


    for (int i = 0; i < numOfTimePeriods; i++) {
        if (i == 0) {
            shifts[i].ge(timePeriodStaffingLevels[i]).post();
        } else {
            shifts[i].add(shifts[i-1]).ge(timePeriodStaffingLevels[i]).post();
        }
    }

    Solver solver = model.getSolver();
    Solution solution = solver.findSolution();

    System.out.printf("shifts\n");
    for (int i = 0; i < shifts.length; i++) {
        System.out.printf("shifts[%d] = %d\n", i, shifts[i].getValue());
    }
    if(solution != null){

        for(IntVar var: model.retrieveIntVars(true)){
            System.out.printf("%s\n", var);
        }

        System.out.printf("Solution\n");
        solver.printStatistics();

    } else {
        for(IntVar var: model.retrieveIntVars(true)){
            System.out.printf("%s\n", var);
        }
    }
} 

public static void main(String[] args) {
    new PredictStaffingLevel2().modelAndSolve();
}

}