171. Excel Sheet Column Number
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
...
class Solution {
public int titleToNumber(String s) {
char[] ch=s.toCharArray();
int res=0;
for(int i=ch.length-1;i>=0;i--){
res+=(ch[i]-'A'+1)*Math.pow(26,ch.length-1-i);
}
return res;
}
}