leetcode 171. Excel Sheet Column Number

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171. Excel Sheet Column Number

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Total Accepted: 66268 Total Submissions: 164127 Difficulty: Easy

Related to question Excel Sheet Column Title

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 

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

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class Solution {
public:
    int titleToNumber(string s) {
        string::reverse_iterator it;
        int ans = 0;
        int temp = 1;
        for(it = s.rbegin();it != s.rend(); it++){
            ans += ( (*it) - 'A' + 1 ) * temp;
            temp *= 26;
        }
        return ans;
    }
};

转另外一个思路：

http://www.cnblogs.com/ganganloveu/p/4191180.html

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