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"
public class Solution {
public string ConvertToTitle(int n) {
var sb = new StringBuilder();
while(n>0){
int mod = (n%26==0?26:n%26);
char ch = (char) (64+mod);
sb.Append(ch.ToString());
n = (n%26==0? n/26-1: n/26);
}
var res = sb.ToString();
return Reverse(res);
}
public static string Reverse( string s )
{
char[] charArray = s.ToCharArray();
Array.Reverse( charArray );
return new string( charArray );
}
}Time Complexity: O(n)
Space Complexity: O(1)
