2015.1.23 17:54

Related to question 

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

Solution:

　　This is a reversed version of the paired question. So do it backward.

Accepted code:

1 // 1AC, nice and easy 2 class Solution { 3 public: 4     int titleToNumber(string s) { 5         int base = 1; 6         int i; 7         int len = s.length(); 8         int sum = 0; 9         10         for (i = 0; i < len; ++i) {11             sum = sum * 26 + (s[i] - 'A');12         }13         for (i = 1; i < len; ++i) {14             base *= 26;15             sum += base;16         }17         sum += 1;18         19         return sum;20     }21 };