【Leetcode】171. Excel Sheet Column Number

public class Solution {
public int titleToNumber(String s) {
int result = 0, len = s.length();
for (int i = 0; i < len; i++)
result = result * 26 + s.charAt(i) - 'A' + 1;
return result;
}
}

public class Solution {
public int titleToNumber(String s) {
int result = 0, len = s.length();
if (len == 1)
return s.charAt(0) - 'A' + 1;
return titleToNumber(s.substring(0, len - 1)) * 26 + s.charAt(len - 1) - 'A' + 1;
}
}