LeetCode/171. ExcelSheetColumnNumber

Link

• https://leetcode.com/problems/excel-sheet-column-number/

Summary

This is the next series of ExcelSheetColumnTitle. Doesn’t took a long time. But I was thinking in a wrong way, doesn’t need to use Maht.Pow. Always good to think a simple & concise solution in arithmetic.

Solutions

My Solution

public int TitleToNumber(string s)
{
    var output = 0;
    var pow = 0;

    while (!String.IsNullOrEmpty(s))
    {
        var lastChar = s[s.Length - 1];
        output += ((lastChar + 1) - 65) * (int)Math.Pow(26, pow);
        pow++;
        s = s.Substring(0, s.Length - 1);
    }

    return output;
}

Best Solution

// Best Solutions
public int BestTitleToNumber(string s)
{
    int result = 0;
    for (int i = 0; i < s.Length; i++)
    {
        result = result * 26 + (s[i] - 'A' + 1);
    }
    return result;
}