Adding Efficient Solution - Problem 171 - Excel Column number

Author: Vanditg

Excel_Column_Number/EfficientSolution.py

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+##==================================
+## Leetcode
+## Student: Vandit Jyotindra Gajjar
+## Year: 2020
+## Problem: 171
+## Problem Name: Excel Sheet Column Number        
+##===================================
+#
+#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): 
+        tmp = 0	#Initialize tmp
+        for i in range(len(s)):	#Loop through string 
+            tmp *= 26	#Update tmp by multiplying with 26(A to Z)
+            tmp += ord(s[i]) - ord('A') + 1	#Update tmp by finding unicode value for given s[i] and subtact from A and add 1
+        return tmp	#Return tmp