tasks a-s

Task/Semordnilap/Tcl/semordnilap.tcl

@@ -0,0 +1,30 @@
+package require Tcl 8.5
+package require http
+
+# Fetch the words
+set t [http::geturl http://www.puzzlers.org/pub/wordlists/unixdict.txt]
+set wordlist [split [http::data $t] \n]
+http::cleanup $t
+
+# Build hash table for speed
+foreach word $wordlist {
+    set reversed([string reverse $word]) "dummy"
+}
+
+# Find where a reversal exists
+foreach word $wordlist {
+    if {[info exists reversed($word)] && $word ne [string reverse $word]} {
+	# Remove to prevent pairs from being printed twice
+	unset reversed([string reverse $word])
+	# Add to collection of pairs
+	set pairs($word/[string reverse $word]) "dummy"
+    }
+}
+set pairlist [array names pairs] ;# NB: pairs are in *arbitrary* order
+
+# Report what we've found
+puts "Found [llength $pairlist] reversed pairs"
+foreach pair $pairlist {
+    puts "Example: $pair"
+    if {[incr i]>=5} break
+}