LeetCode -- Excel Sheet Column Number

LeetCode -- Excel Sheet Column Number
Description:


Related to question Excel Sheet Column Title


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


This question can be converted into a hexadecimal conversion problem.


Train of Thought: it is a bit similar to binary. for AAA, it can be understood as a conversion of binary: 1*26 + 1*26 ^ 2 + 1*26 ^ 3




Implementation Code:

Public class Solution {public int TitleToNumber (string s) {var sum = 0; for (var I = s. length-1; I> = 0; I --) {var d = s. length-I; var n = Num (s [I]); sum + = (int) Math. pow (26, D-1) * n;} return sum;} private int Num (char c) {return (int) c-64 ;}}