[LeetCode] 168. Excel Sheet Column Title

轉自LeetCode

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 

<Solution>
這題就是要把數字轉成對應的文字

可以想成將10進位，變成26進位

想法如下

• 從低位往高位做

• 取餘數，並轉換成字母

• n 除以 26，值到變成 0 為止

code如下(參考資料)
c++

	class Solution {
	public:
	string convertToTitle(int n) {
	string ans;
	while(n) {
	ans.insert(ans.begin(), static_cast<char>(--n % 26 + 'A'));
	n /= 26;
	}
	return ans;
	}
	};

view raw numberToCharMapping_1.cpp hosted with ❤ by GitHub

kotlin

	class Solution {
	fun convertToTitle(n: Int): String {
	val sb = StringBuilder()
	var cnt = n
	while(cnt > 0) {
	val char = 'A' + (--cnt % 26)
	sb.append(char)
	cnt /= 26
	}
	return sb.toString().reversed()
	}
	}

view raw excel_sheet_column_title.kt hosted with ❤ by GitHub