c34026b101
note: done using ```sh git grep -l "2010-2024 Google" | xargs sed -i 's/2010-2024 Google/2010-2025 Google/' ```
123 lines
4.5 KiB
Python
Executable File
123 lines
4.5 KiB
Python
Executable File
#!/usr/bin/env python3
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# Copyright 2010-2025 Google LLC
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""This is the zebra problem as invented by Lewis Caroll.
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There are five houses.
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The Englishman lives in the red house.
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The Spaniard owns the dog.
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Coffee is drunk in the green house.
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The Ukrainian drinks tea.
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The green house is immediately to the right of the ivory house.
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The Old Gold smoker owns snails.
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Kools are smoked in the yellow house.
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Milk is drunk in the middle house.
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The Norwegian lives in the first house.
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The man who smokes Chesterfields lives in the house next to the man
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with the fox.
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Kools are smoked in the house next to the house where the horse is kept.
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The Lucky Strike smoker drinks orange juice.
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The Japanese smokes Parliaments.
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The Norwegian lives next to the blue house.
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Who owns a zebra and who drinks water?
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"""
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from ortools.sat.python import cp_model
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# pylint: disable=too-many-statements
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def solve_zebra():
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"""Solves the zebra problem."""
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# Create the model.
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model = cp_model.CpModel()
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red = model.new_int_var(1, 5, "red")
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green = model.new_int_var(1, 5, "green")
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yellow = model.new_int_var(1, 5, "yellow")
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blue = model.new_int_var(1, 5, "blue")
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ivory = model.new_int_var(1, 5, "ivory")
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englishman = model.new_int_var(1, 5, "englishman")
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spaniard = model.new_int_var(1, 5, "spaniard")
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japanese = model.new_int_var(1, 5, "japanese")
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ukrainian = model.new_int_var(1, 5, "ukrainian")
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norwegian = model.new_int_var(1, 5, "norwegian")
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dog = model.new_int_var(1, 5, "dog")
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snails = model.new_int_var(1, 5, "snails")
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fox = model.new_int_var(1, 5, "fox")
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zebra = model.new_int_var(1, 5, "zebra")
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horse = model.new_int_var(1, 5, "horse")
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tea = model.new_int_var(1, 5, "tea")
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coffee = model.new_int_var(1, 5, "coffee")
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water = model.new_int_var(1, 5, "water")
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milk = model.new_int_var(1, 5, "milk")
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fruit_juice = model.new_int_var(1, 5, "fruit juice")
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old_gold = model.new_int_var(1, 5, "old gold")
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kools = model.new_int_var(1, 5, "kools")
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chesterfields = model.new_int_var(1, 5, "chesterfields")
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lucky_strike = model.new_int_var(1, 5, "lucky strike")
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parliaments = model.new_int_var(1, 5, "parliaments")
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model.add_all_different(red, green, yellow, blue, ivory)
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model.add_all_different(englishman, spaniard, japanese, ukrainian, norwegian)
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model.add_all_different(dog, snails, fox, zebra, horse)
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model.add_all_different(tea, coffee, water, milk, fruit_juice)
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model.add_all_different(parliaments, kools, chesterfields, lucky_strike, old_gold)
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model.add(englishman == red)
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model.add(spaniard == dog)
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model.add(coffee == green)
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model.add(ukrainian == tea)
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model.add(green == ivory + 1)
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model.add(old_gold == snails)
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model.add(kools == yellow)
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model.add(milk == 3)
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model.add(norwegian == 1)
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diff_fox_chesterfields = model.new_int_var(-4, 4, "diff_fox_chesterfields")
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model.add(diff_fox_chesterfields == fox - chesterfields)
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model.add_abs_equality(1, diff_fox_chesterfields)
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diff_horse_kools = model.new_int_var(-4, 4, "diff_horse_kools")
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model.add(diff_horse_kools == horse - kools)
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model.add_abs_equality(1, diff_horse_kools)
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model.add(lucky_strike == fruit_juice)
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model.add(japanese == parliaments)
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diff_norwegian_blue = model.new_int_var(-4, 4, "diff_norwegian_blue")
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model.add(diff_norwegian_blue == norwegian - blue)
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model.add_abs_equality(1, diff_norwegian_blue)
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# Solve and print out the solution.
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solver = cp_model.CpSolver()
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status = solver.solve(model)
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if status == cp_model.OPTIMAL:
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people = [englishman, spaniard, japanese, ukrainian, norwegian]
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water_drinker = [p for p in people if solver.value(p) == solver.value(water)][0]
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zebra_owner = [p for p in people if solver.value(p) == solver.value(zebra)][0]
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print("The", water_drinker.name, "drinks water.")
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print("The", zebra_owner.name, "owns the zebra.")
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else:
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print("No solutions to the zebra problem, this is unusual!")
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solve_zebra()
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