Add No_171: Excel Sheet Column Number

Author: brianchiang-tw

No_171_Excel Sheet Column Number/No_171_Excel Sheet Column Number_description.py

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+'''
+
+Description:
+
+Given a column title as appear in an Excel sheet, return its corresponding column number.
+
+For example:
+
+    A -> 1
+    B -> 2
+    C -> 3
+    ...
+    Z -> 26
+    AA -> 27
+    AB -> 28 
+    ...
+Example 1:
+
+Input: "A"
+Output: 1
+Example 2:
+
+Input: "AB"
+Output: 28
+Example 3:
+
+Input: "ZY"
+Output: 701
+
+'''

No_171_Excel Sheet Column Number/excel_sheet_column_number_by_recursion.py

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+'''
+
+Description:
+
+Given a column title as appear in an Excel sheet, return its corresponding column number.
+
+For example:
+
+    A -> 1
+    B -> 2
+    C -> 3
+    ...
+    Z -> 26
+    AA -> 27
+    AB -> 28 
+    ...
+Example 1:
+
+Input: "A"
+Output: 1
+Example 2:
+
+Input: "AB"
+Output: 28
+Example 3:
+
+Input: "ZY"
+Output: 701
+
+'''
+
+
+
+class Solution:
+    def titleToNumber(self, s: str) -> int:
+        
+        if len(s) == 1:
+            # base case
+            return ord(s)-64
+
+        else:
+            # general case
+            return 26*self.titleToNumber( s[:-1] ) + self.titleToNumber( s[-1] )
+
+
+
+# n : the length of input string s
+
+## Time Complexity: O( n )
+#
+# The major overhead in time is the call depth of recursion, which is of O( n ).
+
+## Space Complexity: O( n )
+#
+# The major overhead in space is to maintain call stack for recursion, which is of O( n ).
+
+
+
+def test_bench():
+
+    test_data = ['A', 'AB', 'AZ', 'BA','ZY', 'ZZ','AAA']
+
+    for s in test_data:
+
+        n = Solution().titleToNumber(s)
+        print(n)
+
+    return
+
+
+
+if __name__ == '__main__':
+
+    test_bench()