package cn.edu.xidian.sselab;
/**
* title:Excel sheet Column Title
* content:
* 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
*/
public class ConvertToTitle {
//自己想的，这种方法虽然对，但是代码量比较多，看上去比较麻烦
//这里分两种情况来考虑的，（1）26的整数倍（2）不是26的倍数
//（1）当是26的整数倍的时候，还要考虑商是1的情况，不进位，商大于1时才进行进位操作
//(2)当不是26的整数倍的时候
public static String converToTitle(int n){
String title = "";
int remainder;
if(n % 26 == 0){
while(n % 26 == 0){
title = (char) 'Z' + title;
n = n / 26;
}
if(n > 1){
title = (char) (n - 2 + 'A') + title;
}
}else{
while(n > 26){
remainder = n % 26;
n = n / 26;
title = (char) (remainder - 1 + 'A') + title;
}
title = (char) (n - 1 + 'A') + title;
}
return title;
}
//参考的比较好的方法,唯一的问题是：满足26的倍数，发生进位操作，26的倍数个数就减一
public String convertToTitles(int n){
StringBuffer sb = new StringBuffer();
int remainder;
while(n > 0){
remainder = n % 26;
n = n / 26;
if(remainder != 0){
sb.append((char)(remainder - 1 + 'A'));
}else{
sb.append('Z');
n--;
}
}
return sb.reverse().toString();
}
}