171. Excel Sheet Column Number（LeetCode）

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 
还是接着上一篇，自己的“笨”方法：

 1 class Solution {
 2 public:
 3     int titleToNumber(string s) {
 4         map<char,int> m;
 5         string str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
 6         for (int i = 1; i <= 26; i++)
 7         {
 8             cout << str[i - 1];
 9             m.insert(pair<char, int>(str[i - 1], i));
10         }
11         int len = s.size();
12         int len1 = len;
13         int sum1 = 0;
14         for (int i = 0; i<len; i--)
15         {
16             int sum = 1;
17             for (int i = 1; i < len1; i++)
18             {
19                 sum *= 26;
20             }
21             sum1 += m[s[i]] * sum;
22             len1--;
23         }
24         return sum1;
25     }
26 };

别人的方法：

 1 class Solution {
 2 public:
 3     int titleToNumber(string s) {
 4         int result = 0;
 5         int carrier = 1;
 6         for (int i = 0; i < s.size(); i++) {
 7             result += (s[s.size() - i - 1] - 64) * carrier;
 8             carrier *= 26;
 9         }
10         return result;
11     }
12 };