Create manachar_algorithm.py

Author: the-ethan-hunt

Competitive Coding/Strings/String Search/Manachar_algorithm/manachar_algorithm.py

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+def get_palindrome_length(string, index):
+    length = 1
+    while index + length < len(string) and index - length >= 0:
+        if string[index + length] == string[index - length]:
+            length += 1
+        else:
+            break
+        return length - 1
+
+def interleave(string):
+    ret = []
+    for s in string:
+        ret.extend(['#', s])
+    ret.append('#')
+    return ''.join(ret)
+
+def manacher(string):
+    right = 0
+    center = 0
+    string = interleave(string)
+    P = map(lambda e: 0, xrange(len(string)))
+    for i in xrange(1, len(string)):
+        mirror = 2*center - i
+        if i + P[mirror] <= right and mirror >= len(string) - i:
+            P[i] = P[mirror]
+        else:
+            plength = get_palindrome_length(string, i)
+            P[i] = plength
+            if plength > 1:
+                center = int(i)
+                right = center + plength
+    return [e/2 for e in P]
+
+def get_palindrome_number(string):
+    return sum(manacher(string))