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Task/Penneys-game/UNIX-Shell/penneys-game.sh

@@ -0,0 +1,70 @@
+#!/bin/bash
+main() {
+  echo "Penney's Game"
+  echo -n "Flipping to see who goes first ... "
+
+  if [[ $(flip) == H ]]; then
+    echo "I do."
+    p2=$(choose_sequence)
+    echo "I choose: $p2"
+  else
+    echo "You do."
+  fi
+
+  while true; do
+    echo "Enter your three-flip sequence:"
+    read p1
+    case "$p1" in
+     "$p2") echo "Sequence must be different from mine";;
+     [hHTt][hHtT][hHtT]) break;;
+     *) echo "Sequence must be three H's or T's";;
+    esac
+  done
+  p1=$(tr a-z A-Z <<<"$p1")
+
+  if [ -z "$p2" ]; then
+    p2=$(choose_sequence "$p1")
+    echo "I choose: $p2"
+  fi
+
+  echo
+  echo "Here we go.  $p1, you win; $p2, I win."
+  flips=
+
+  while true; do
+    flip=$(flip)
+    echo -n $flip
+    flips+=$flip
+    while (( ${#flips} > 3 )); do
+      flips="${flips#?}"
+    done
+    case "$flips" in
+      *$p1) echo $'\nYou win!'; exit 0;;
+      *$p2) echo $'\nI win!'; exit 1;;
+    esac
+  done
+}
+
+choose_sequence() {
+  local result
+  if (( $# )); then
+    case "$1" in
+      ?Hh?) result=T;;
+      *) result=H;;
+    esac
+    result+="${1%?}"
+  else
+    result=$(flip)$(flip)$(flip)
+  fi
+  echo "$result"
+}
+
+flip() {
+  if (( RANDOM % 2 )); then
+    echo H
+  else
+    echo T
+  fi
+}
+
+main "$@"