171. Excel Sheet Column Number (Math)
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
class Solution { public: int titleToNumber(string s) { //the last bit of s, multiply 26 //then left move 1 bit, multiply 26^2 //iterate int len = s.length(); int ret = 0; int multiplier = 1; int cur; for(int i = len-1; i >= 0; i--){ cur = s[i]-'A'+1; ret += cur*multiplier; multiplier *= 26; } return ret; } };