LeetCode: 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.

A -> 1 B -> 2 C -> 3 ... Z -> 26 AA -> 27 AB -> 28

For example:

A -> 1
B -> 2
C -> 3
...
Z -> 26
AA -> 27
AB -> 28

题目解析：以26为一个进制，进行叠加即可。

源代码：

int titleToNumber(char* s) {
int len = strlen(s);
int res = 0;
for (int i = 0; i < len; ++i) {
res *= 26;
res += s[i] - 'A' + 1;
}

return res;

}