added rest of the code

19/part1.py

@@ -0,0 +1,53 @@
+#!/usr/bin/python
+
+import re
+
+RE_RULE = re.compile(r'^(.*) => (.*)$')
+
+
+def read_file(filename):
+    file = open(filename, 'r')
+    while True:
+        line = file.readline()
+        if not line:
+            break
+        yield line.strip()
+
+
+def apply_rule(formula, key, value):
+    keyLen = len(key)
+    formulaPos = 0
+
+#    print "formula: %s, key: %s, value: %s" % (formula, key, value)
+    while True:
+        pos = formula.find(key, formulaPos)
+#        print " - pos: %d" % (pos)
+        if pos < 0:
+            break
+        yield formula[0:pos] + value + formula[pos+keyLen:]
+        formulaPos = pos + keyLen
+
+
+def main():
+    formula = ""
+    rules = dict()
+    for line in read_file('input'):
+        # skip empty lines
+        if not line:
+            continue
+        match = re.match(RE_RULE, line)
+        if match:
+            if match.group(1) not in rules:
+                rules[match.group(1)] = []
+            rules[match.group(1)].append(match.group(2))
+        else:
+            formula = line
+
+    for k1, v1 in rules.iteritems():
+        for v2 in v1:
+            for r in apply_rule(formula, k1, v2):
+                print r
+
+
+if __name__ == "__main__":
+    main()