LeetCode in Kotlin

171. Excel Sheet Column Number

Easy

Given a string columnTitle that represents the column title as appears 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: columnTitle = “A”

Output: 1

Example 2:

Input: columnTitle = “AB”

Output: 28

Example 3:

Input: columnTitle = “ZY”

Output: 701

Constraints:

• 1 <= columnTitle.length <= 7
• columnTitle consists only of uppercase English letters.
• columnTitle is in the range ["A", "FXSHRXW"].

Solution

class Solution {
    fun titleToNumber(s: String): Int {
        var num = 0
        var pow = 0
        for (i in s.length - 1 downTo 0) {
            num += Math.pow(26.0, pow++.toDouble()).toInt() * (s[i].code - 'A'.code + 1)
        }
        return num
    }
}

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