examples/notebook/contrib/just_forgotten.ipynb
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First, you must install ortools package in this colab.
%pip install ortools
Just forgotten puzzle (Enigma 1517) in Google CP Solver.
From http://www.f1compiler.com/samples/Enigma 201517.f1.html ''' Enigma 1517 Bob Walker, New Scientist magazine, October 25, 2008.
Joe was furious when he forgot one of his bank account numbers. He remembered that it had all the digits 0 to 9 in some order, so he tried the following four sets without success:
9 4 6 2 1 5 7 8 3 0
8 6 0 4 3 9 1 2 5 7
1 6 4 0 2 9 7 8 5 3
6 8 2 4 3 1 9 0 7 5
When Joe finally remembered his account number, he realised that in each set just four of the digits were in their correct position and that, if one knew that, it was possible to work out his account number. What was it? '''
Compare with the following models:
This model was created by Hakan Kjellerstrand ([email protected]) Also see my other Google CP Solver models: http://www.hakank.org/google_or_tools/
from ortools.constraint_solver import pywrapcp
def main():
# Create the solver.
solver = pywrapcp.Solver("Just forgotten")
#
# data
#
rows = 4
cols = 10
# The four tries
a = [[9, 4, 6, 2, 1, 5, 7, 8, 3, 0], [8, 6, 0, 4, 3, 9, 1, 2, 5, 7],
[1, 6, 4, 0, 2, 9, 7, 8, 5, 3], [6, 8, 2, 4, 3, 1, 9, 0, 7, 5]]
#
# variables
#
x = [solver.IntVar(0, 9, "x[%i]" % j) for j in range(cols)]
#
# constraints
#
solver.Add(solver.AllDifferent(x))
for r in range(rows):
b = [solver.IsEqualCstVar(x[c], a[r][c]) for c in range(cols)]
solver.Add(solver.Sum(b) == 4)
#
# search and result
#
db = solver.Phase(x, solver.INT_VAR_SIMPLE, solver.INT_VALUE_DEFAULT)
solver.NewSearch(db)
num_solutions = 0
while solver.NextSolution():
num_solutions += 1
xval = [x[j].Value() for j in range(cols)]
print("Account number:")
for j in range(cols):
print("%i " % xval[j], end=" ")
print()
print("\nThe four tries, where '!' represents a correct digit:")
for i in range(rows):
for j in range(cols):
check = " "
if a[i][j] == xval[j]:
check = "!"
print("%i%s" % (a[i][j], check), end=" ")
print()
print()
print()
solver.EndSearch()
print("num_solutions:", num_solutions)
print("failures:", solver.Failures())
print("branches:", solver.Branches())
print("WallTime:", solver.WallTime())
main()