leetcode 168. Excel Sheet Column Title 171 Excel Sheet Column Number

题目

//像10进制一样进行 转换   只是要从0开始记录

class Solution {
public:
    string convertToTitle(int n) {
        char a;
        string str="";
        while(n>0){
            int tmp = (n-1)%26;
            str = char(tmp+'A') + str;
            n = (n-1)/26;
        } 
        return str;
    }
};

 171  Excel Sheet Column Number

class Solution {
public:
    int titleToNumber(string s) {
        int n = s.size();
        int sum = 0;
        for(int i = 0; i<n; i++){
            int tmp = s[i]-'A' + 1;
            sum = sum * 26 + tmp;
        }
        return sum;
    }
};