1 files changed, 132 insertions, 0 deletions
diff --git a/challenge-007/zapwai/python/ch-2.py b/challenge-007/zapwai/python/ch-2.py
new file mode 100644
index 0000000000..cd816028fc
--- /dev/null
+++ b/challenge-007/zapwai/python/ch-2.py
@@ -0,0 +1,132 @@
+import re
+
+def quit():
+    print("Output: ()")
+
+def read_file(filename):
+    fh = open(filename, "r")
+    words = []
+    for x in fh:
+        y = x.rstrip('\r\n');
+        words.append(y)
+    return words
+
+def neighbor(word, word_list):
+    for w in word_list:
+        if dist(w, word) == 1:
+            return w
+
+def dist(word1, word2):
+    cnt = 0
+    for i in range(len(word1)):
+        if word1[i] != word2[i]:
+            cnt += 1
+    return cnt
+
+def check(m, n, A, B):
+    ans = []
+    for i in range(m+1):
+        for j in range(n+1):
+            a = intersection(A[i], B[j])
+            if len(a) > 0:
+                for ick in a:
+                    ans.append(ick)
+    return ans
+
+def expand(word, words):
+    new = []
+    for i in range(len(word)):
+        pre = word[0:i]
+        post = word[i+1:]
+        for w in words:
+            pattern = str(pre) + "." + str(post)
+            if re.search(pattern, w):
+                new.append(w)
+                
+    anew = [item for item in new if item != word]
+    return anew
+
+
+def intersection(A, B):
+    int = []
+    for i in range(len(A)):
+        for j in range(len(B)):
+            if A[i] == B[j]:
+                int.append(A[i])
+    return int
+
+def proc(input1, input2):
+    limit = 4                   # max-length of chain is 2*limit
+
+    print("Input:", input1, input2)
+    if len(input1) != len(input2):
+        return quit()
+    filename = "words"
+    dicts = read_file(filename)
+
+    cnt = 0
+    for word in dicts:
+        if re.search("^"+input2+"$", word) or re.search("^"+input1+"$", word):
+            cnt += 1
+    if cnt < 2:
+        print("One of these inputs is not a word.")
+        return quit()
+        
+    wordlen = len(input1)
+    words = []
+    for d in dicts:
+        if len(d) == wordlen:
+            words.append(d)
+
+    A = [[input1]]
+    B = [[input2]]
+
+    center = []
+    lvl = 0
+    while lvl < limit and not center:
+        anew = []; bnew = []
+        for wa in A[lvl]:
+            for w in expand(wa, words):
+                anew.append(w)
+        for wb in B[lvl]:
+            for w in expand(wb, words):
+                bnew.append(w)
+
+        uniq_a = []
+        uniq_b = []
+        for item in anew:
+            if item not in uniq_a:
+                uniq_a.append(item)
+        for item in bnew:
+            if item not in uniq_b:
+                uniq_b.append(item)
+
+        A.append(uniq_a)
+        B.append(uniq_b)
+        lvl += 1
+        center = check(lvl, lvl, A, B)
+    if lvl == limit:
+        return quit()
+    counter = lvl - 1
+    mylist = [center[0]]
+    x = neighbor(center[0], A[counter])
+    y = neighbor(center[0], B[counter])
+    if y is not None:
+        while counter > 0:
+            mylist = [x] + mylist
+            mylist.append(y)
+            counter -= 1
+            x = neighbor(x, A[counter])
+            y = neighbor(y, B[counter])
+
+    if x is not None:
+        mylist = [x] + mylist
+    if y is not None:
+        mylist.append(y)
+    print("Output:", mylist)
+    
+l1 = ["pour", "cold", "peer", "knife", "prince"]
+l2 = ["made", "warm", "norm", "dance", "prance"]
+for i in range(len(l1)):
+    proc(l1[i], l2[i])
+