# Daily Coding Challenge #89

This is a series of Daily Coding Challenge. Each day I show a few solutions written in C++. The questions are from coding practice/contest sites such as HackerRank, LeetCode, Codeforces, Atcoder and etc.

/*
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
...
Example 1:

Input: "A"
Output: 1
Example 2:

Input: "AB"
Output: 28
Example 3:

Input: "ZY"
Output: 701

Constraints:

1 <= s.length <= 7
s consists only of uppercase English letters.
s is between "A" and "FXSHRXW".
*/

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



/*
Excel Sheet Column Title

Given a positive integer, return its corresponding column title as appear in an Excel sheet.

For example:

1 -> A
2 -> B
3 -> C
...
26 -> Z
27 -> AA
28 -> AB
...
Example 1:

Input: 1
Output: "A"
Example 2:

Input: 28
Output: "AB"
Example 3:

Input: 701
Output: "ZY"
*/

class Solution {
public:
string convertToTitle(int n) {
if(--n<26) return string(1,n+65);
return convertToTitle(n/26)+string(1,n%26+65);
}
};


The source code is available in corresponding repo below. Star and watch for timely updates!

## wingkwong / atcoder

### Discussion   