leetcode 171

Posted 2020-08-17

171. Excel Sheet Column Number

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 

从A到Z依次代表从1到26，按照26进制进位。
代码如下：

 1 class Solution {
 2 public:
 3     int titleToNumber(string s) {
 4         int n = s.length();
 5         int m = n;
 6         int result = 0;
 7         if(n == 0)
 8         {
 9             return 0;
10         }
11         result = (int)s[m-1];
12         result -= 64;
13         for(int i = 1; i < n+1; i++)
14         {
15             m--;
16             if(m == 0)
17             {
18                 return result;
19             }
20             int p = 1;
21             for(int j = 0; j < i; j++)
22             {
23                 p *= 26;
24             }
25             int re = (int)s[m-1];
26             re -= 64;
27             result = result + re * p;
28         }
29         return result;
30     }
31 };