LeetCode 171. Excel Sheet Column Number

分析

难度 易

来源

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

题目

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

解答

Runtime: 1 ms, faster than 100.00% of Java online submissions for Excel Sheet Column Number.

package LeetCode;

public class L171_ExcelSheetColumnNumber {
    public int titleToNumber(String s) {
        int len=s.length();
        int colNum=0;
        int base=1;//当前位的1表示的大小
        for(int i=len-1;i>=0;i--){
            colNum+=(int)(s.charAt(i)-64)*base;
            base*=26;
        }
        return colNum;
    }
    public static void main(String[] args){
        L171_ExcelSheetColumnNumber l171=new L171_ExcelSheetColumnNumber();
        String s="AB";
        System.out.println(l171.titleToNumber(s));
    }
}