gate scheduling problem

2017-10-17 11:42:24 +02:00
parent a54b49ebb8
commit 2152b57799
1 changed files with 101 additions and 0 deletions
--- a/examples/python/gate_scheduling_sat.py
+++ b/examples/python/gate_scheduling_sat.py
@@ -0,0 +1,101 @@
+# Copyright 2010-2017 Google
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from ortools.sat.python import cp_model
+
+
+def main():
+  model = cp_model.CpModel()
+
+  jobs = [[3, 3],
+          [2, 5],
+          [1, 3],
+          [3, 7],
+          [7, 3],
+          [2, 2],
+          [2, 2],
+          [5, 5],
+          [10, 2],
+          [4, 3],
+          [2, 6],
+          [1, 2],
+          [6, 8],
+          [4, 5],
+          [3, 7]]
+
+  max_length = 10
+
+  horizon = sum(t[0] for t in jobs)
+  num_jobs = len(jobs)
+  all_jobs = range(num_jobs)
+
+  intervals = []
+  intervals0 = []
+  intervals1 = []
+  performed = []
+  starts = []
+  ends = []
+  demands = []
+
+  for i in all_jobs:
+    start = model.NewIntVar(0, horizon, 'start_%i' % i)
+    duration = jobs[i][0]
+    end = model.NewIntVar(0, horizon, 'end_%i' % i)
+    interval = model.NewIntervalVar(start, duration, end, 'interval_%i' % i)
+    starts.append(start)
+    intervals.append(interval)
+    ends.append(end)
+    demands.append(jobs[i][1])
+
+    performed_on_m0 = model.NewBoolVar('perform_%i_on_m0' % i)
+    performed.append(performed_on_m0)
+    start0 = model.NewIntVar(0, horizon, 'start_%i_on_m0' % i)
+    end0 = model.NewIntVar(0, horizon, 'end_%i_on_m0' % i)
+    interval0 = model.NewOptionalIntervalVar(
+        start0, duration, end0, performed_on_m0, 'interval_%i_on_m0' % i)
+    intervals0.append(interval0)
+
+    start1 = model.NewIntVar(0, horizon, 'start_%i_on_m1' % i)
+    end1 = model.NewIntVar(0, horizon, 'end_%i_on_m1' % i)
+    interval1 = model.NewOptionalIntervalVar(
+        start1, duration, end1, performed_on_m0.Not(), 'interval_%i_on_m1' % i)
+    intervals1.append(interval1)
+
+    # We only propagate the constraint if the tasks is performed on the machine.
+    model.Add(start0 == start).OnlyEnforceIf(performed_on_m0)
+    model.Add(start1 == start).OnlyEnforceIf(performed_on_m0.Not())
+
+  # Max Length constraint (modeled as a cumulative)
+  model.AddCumulative(intervals, demands, max_length)
+
+  # Choose which machine to perform the jobs on.
+  model.AddNoOverlap(intervals0)
+  model.AddNoOverlap(intervals1)
+
+  # Objective variable.
+  makespan = model.NewIntVar(0, horizon, 'makespan')
+  model.AddMaxEquality(makespan, ends)
+  model.Minimize(makespan)
+
+  # Solve model.
+  solver = cp_model.CpSolver()
+  solver.Solve(model)
+  print('Makespan = %i' % solver.ObjectiveValue())
+  for i in all_jobs:
+    performed_machine = 1 - solver.Value(performed[i])
+    start = solver.Value(starts[i])
+    print('Job %i starts at %i on machine %i' % (i, start, performed_machine))
+
+
+if __name__ == '__main__':
+  main()