ssangervasi
diff --git a/‎strings/longest_substring.py
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+34Lines changed: 34 additions & 0 deletions b/‎strings/longest_substring.py
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+34Lines changed: 34 additions & 0 deletions
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+# Create an algorithm that prints the longest substring of s in which
+# the letters occur in alphabetical order. For example, if
+# s = 'azcbobobegghakl', then your program should print:
+# Longest substring in alphabetical order is: beggh
+
+# In the case of ties, print the first substring.
+# For example, if s = 'abcbcd', then your program should print:
+# Longest substring in alphabetical order is: abc
+
+
+def longest_substr(s):
+    count = 0
+    maxcount = 0
+    result = 0
+    for char in range(len(s) - 1):
+        if (s[char] <= s[char + 1]):
+            count += 1
+            if count > maxcount:
+                maxcount = count
+                result = char + 1
+        else:
+            count = 0
+    startposition = result - maxcount
+    return startposition, result
+
+
+# parent string
+s = 'azbeggaklbeggh'
+
+# longest substring indexes
+start, end = longest_substr(s)
+
+print('Longest substring in alphabetical order is:',
+      s[start:end + 1])