LeetCode之171. Excel Sheet Column Number

public class Solution {
    public int titleToNumber(String s) {
        int res=0;
        for(int i=s.length()-1;i>=0;i--) res+=(s.charAt(i)-‘A‘+1)*((int)(Math.pow(26,s.length()-i-1)));
        return res;
    }
}

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