Bash solution for week 109, part 2

1 files changed, 83 insertions, 0 deletions

diff --git a/challenge-109/abigail/bash/ch-2.sh b/challenge-109/abigail/bash/ch-2.sh
new file mode 100644
index 0000000000..175ddf807d
--- /dev/null
+++ b/challenge-109/abigail/bash/ch-2.sh
@@ -0,0 +1,83 @@
+#!/bin/sh
+
+#
+# See ../README.md
+#
+
+#
+# Run as: bash ch-2.sh < input-file
+#
+
+SIZE=7
+
+#
+# Just try all possibilities, but continue as soon as we know
+# this cannot lead to a solution.
+#
+# We use 7 variables, a_i .. g_i indicating the indices of of
+# the numbers we try for a .. g. We use nested loops to iterate
+# over all the possibilties. We continue with the next iteration
+# of a loop if:
+#
+#  - We pick an index which is already taken by an outer loop.
+#  - We have a mismatch in the sums in the squares:
+#       + We define a target = numbers [a_i] + numbers [b_i] 
+#       + After picking c_i and d_i, we check whether 
+#         numbers [b_i] + numbers [c_i] + numbers [d_i] equals target.
+#       + After picking e_i and f_i, we check whether
+#         numbers [d_i] + numbers [e_i] + numbers [f_i] equals target.
+#       + After picking g_i, we check whether
+#         numbers [f_i] + numbers [g_i] equals target.
+#       + If we pass all tests, we have a solution.
+#
+
+while read -a numbers
+do   for ((a_i = 0; a_i < SIZE; a_i ++))
+     do  for ((b_i = 0; b_i < SIZE; b_i ++))
+         do  if   ((a_i == b_i))
+             then continue
+             fi
+             ((target = numbers[a_i] + numbers[b_i]))
+             for ((c_i = 0; c_i < SIZE; c_i ++))
+             do  if   ((a_i == c_i || b_i == c_i))
+                 then continue
+                 fi
+                 for ((d_i = 0; d_i < SIZE; d_i ++))
+                 do  if   ((a_i == d_i || b_i == d_i || c_i == d_i ||
+                            target != numbers[b_i] + numbers[c_i] +
+                                      numbers[d_i]))
+                     then continue
+                     fi
+                     for ((e_i = 0; e_i < SIZE; e_i ++))
+                     do  if   ((a_i == e_i || b_i == e_i ||
+                                c_i == e_i || d_i == e_i))
+                         then continue
+                         fi
+                         for ((f_i = 0; f_i < SIZE; f_i ++))
+                         do  if   ((a_i == f_i || b_i == f_i ||
+                                    c_i == f_i || d_i == f_i ||
+                                    e_i == f_i ||
+                                    target != numbers[d_i] + numbers[e_i] +
+                                              numbers[f_i]))
+                             then continue
+                             fi
+                             for ((g_i = 0; g_i < SIZE; g_i ++))
+                             do  if   ((a_i == g_i || b_i == g_i ||
+                                        c_i == g_i || d_i == g_i ||
+                                        e_i == g_i || f_i == g_i ||
+                                        target != numbers[f_i] + numbers[g_i]))
+                                 then continue
+                                 fi
+                                 printf "%d %d %d %d %d %d %d\n" \
+                                         ${numbers[$a_i]} ${numbers[$b_i]} \
+                                         ${numbers[$c_i]} ${numbers[$d_i]} \
+                                         ${numbers[$e_i]} ${numbers[$f_i]} \
+                                         ${numbers[$g_i]}
+                             done
+                         done
+                     done
+                 done
+             done
+         done
+     done
+done