added rest of the code

19/input1

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+H => HO
+H => OH
+O => HH
+
+HOH

19/input2

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+e => H
+e => O
+H => HO
+H => OH
+O => HH
+
+HOHOHO

19/part1.py

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+#!/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()

19/part2.py

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+#!/usr/bin/python
+
+# solution borrowd from
+# https://www.reddit.com/r/adventofcode/comments/3xflz8/day_19_solutions/?sort=new
+
+import re
+from random import shuffle
+
+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 find_formula(formula, rules):
+    steps = 0
+    f = formula
+    while formula != 'e':
+        start = formula
+        for k,v in rules:
+            if v in formula:
+                steps += 1
+                formula = formula.replace(v, k, 1)
+
+        if formula == start:
+            shuffle(rules)
+            steps = 0
+            formula = f
+
+    return steps
+
+def main():
+    medicine = ""
+    rules = []
+    for line in read_file('input'):
+        # skip empty lines
+        if not line:
+            continue
+        match = re.match(RE_RULE, line)
+        if match:
+            rules.append((match.group(1), match.group(2)))
+        else:
+            medicine = line
+
+    print rules
+    print medicine
+    print find_formula(medicine, rules)
+
+if __name__ == "__main__":
+    main()

19/readme

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+## part1
+
+    python part1.py  | sort -u | wc -l
+
+## part2