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  • LeetCode 168. Excel Sheet Column Title

    原题链接在这里: https://leetcode.com/problems/excel-sheet-column-title/

    题目:

    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 

    题解:

    不是从0开始算,这里是从1算起. 算之前先对n进行n-1处理再取余数。

    Time Complexity: O(res.length()).

    Space: O(res.length()).

    AC Java:

     1 class Solution {
     2     public String convertToTitle(int n) {
     3         if(n <= 0){
     4             throw new IllegalArgumentException("Invalid input integer.");
     5         }
     6         
     7         StringBuilder sb = new StringBuilder();
     8         while(n != 0){
     9             sb.insert(0, (char)('A'+(n-1)%26));
    10             n = (n-1)/26;
    11         }
    12         
    13         return sb.toString();
    14     }
    15 }

    recursion写法.

    Time Complexity: O(res.length()). Space: O(res.length()).

    AC Java:

     1 class Solution {
     2     public String convertToTitle(int n) {
     3         if(n == 0){
     4             return "";
     5         }
     6         
     7         n = n-1;
     8         return convertToTitle(n/26) + (char)('A'+ (n%26));
     9     }
    10 }

    类似Excel Sheet Column Number.

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  • 原文地址:https://www.cnblogs.com/Dylan-Java-NYC/p/4825044.html
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