CareerCup

public class ExcelColumn {

public static String excelColumnName(int num){
        if(num==0)
        	return "";
		if (num<=26)
			return Character.toString((char) (num+64));
		else {
			int firstpart=num/26;
		    int end=num%26;
		    end=end==0?26:end;
		    if (firstpart >26)
		    	return excelColumnName((num-end)/26)+Character.toString((char) (end+64));
		    else
		    	return Character.toString((char) ((num-end)/26+64))+Character.toString((char) (end+64));
		}
		
	}
	public static void main(String[] args) {

		for (int i=24;i<30;i++){
			System.out.println(excelColumnName(i));
		}
		System.out.println(excelColumnName(746));
	}

}



X
Y
Z
AA
AB
AC
ABR

Java Implementation:

public class ReplaceNumberWithExcelLabel {
	public static String convertToExcelLabel (int n) {
		String result = "";
		int index = 0;
	    while (n > 0) {
	    	index = (n - 1) % 26;
	    	result = Character.toChars(index + 65)[0] + result;
	    	n = (n - 1) / 26;
	    }
	    return result;
	}
	
	public static void main(String[] args) {
		System.out.println(convertToExcelLabel(1));
		System.out.println(convertToExcelLabel(55));
	}
}

public class Excel {

	public static char column(int n) {
		int d, r;

		int A = 'A';
		int Z = 'Z';
		int numLetters = Z - A + 1;
		char s = ' ';

		while (n > 0) {
			d = (n - 1) / numLetters;
			r = (n - 1) % numLetters;
			s += A + r;
			n = d;
		}
		return Character.toUpperCase(s);
	}

	public static void main(String[] args) {

		for (int i = 1; i <= 26; i++) {
			System.out.println(column(i));
		}

		for (int i = 1; i <= 26; i++) 			
			for (int j = 1; j <= 26; j++)
				System.out.println(column(i) + "" + column(j));

		for (int i = 1; i <= 26; i++)
			for (int j = 1; j <= 26; j++)
				for (int k = 1; k <= 26; k++)
					System.out.println(column(i) + "" + column(j) + ""
							+ column(k));
	}
}

oh, any suggestions on how to solve?

void ConvertToExcel(int number,char* formatted){
	int i = 0, num=number;
	while (num)
	{
		formatted[i++] = 'A'-1 + num % 26;
		num = num / 26;
	}
	formatted[i--] = '\0';
	for (int p = 0, q = i; p < q; p++, q--){
		char temp = formatted[p];
		formatted[p] = formatted[q];
		formatted[q] = temp;
	}

}

public static String numToColumn(int number){
        
        StringBuilder sb = new StringBuilder();
        char c;
        char s=0;
        int n = number;
        while(n > 0){
            c = (char) ((n - 1) %26);
            s = (char) ((c+65));
            n = (n-c)/26;      
            sb.append(s);
        }
        return sb.toString();
    }

ha, totally right.
sb.reverse().toString() would do. But, I doubt the interviewer would be happy.

final static char[] alpha = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N',
'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };

static int LENGTH = alpha.length;

public static String generatevariable(int a) {
int t = a;
StringBuffer s = new StringBuffer("");
if (a == 0)
return "";
if (a <= LENGTH)
s.append(alpha[a - 1]);
else {
s.append(generatevariable((a - 1) / LENGTH)); // use recursion
s.append(generatevariable(a - ((a - 1) / LENGTH) * LENGTH));
}
return s.toString();
}

def main():
  num = int(input())
  col = ''
  
  while num > 0:
    c = chr((num-1)%26+65)
    col = c+col
    num = (num-1)//26
  
  print(col)
  

if __name__ == '__main__':
  main()

static char [] chars = new char[27];
	static {
		char c = 'A';
		for(int i=0;i<26; i++)
			chars[i] = c++;
	}
	static String getExcelValue(int num) {
		return getExcel(num-1);
	}
	static String getExcel(int num) {
		
		int rem = num % 26;
		int quot = num / 26;
		
		if(quot > 0)
			return getExcel(quot-1) + chars[rem];		
		return ""+chars[rem];
	}

public class ExcelColumn
{
    public static void printColumnName(int n) {
	    if(n/26>0) { // recurse
			printColumnName(n/26-1);
		}
		
		//print character
		System.out.print(Character.toString((char)('A'+n%26)));
	}
	
    public static void main(String[] args) {
		printColumnName(Integer.parseInt(args[0])-1);
	}
}

python code

num=int(raw_input())
result=""
while(num>=0):
    t=num%26
    result=chr(ord("A")+t)+result
    num=num/26 -1
    
print result

public void findXLcolumnByNumber(int number){
		List<Character> lst = new ArrayList<Character>();
		while (number > 0){			
			int b = number % 26;
			number = number / 26;
			b = b == 0 ? 26 : b;
			lst.add((char) (b + 64));
		}
		
		for (int i = lst.size() - 1; i >= 0; i--)System.out.print(lst.get(i));
		System.out.println();
	}

in c++ code

void columeInExcel(int number)
{
	string dic=" ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	vector<char> result;
	while(number)
	{
		int low = number%26;
		int high = number/26;
		if(high == 1 && low == 0)
		{
			result.push_back('z');
			break;
		}
		result.push_back(dic[low]);
		number = high;
	}
	for(int i = result.size()-1; i>=0; i--)
		cout << result[i];
	cout << endl;
}

Did this or something similar some time back, check the below link if you think this help.
ms-amazon.blogspot.in/2013/03/there-is-sequence-where-alphabets-are.html

public class ExcelColumns {

public static String getExcelColumnName(int n){
if(n < 1) return null;
StringBuilder sb = new StringBuilder();
while(n > 0){
sb.append((char)('A'+(n-1)%26));
n= (n-1)/26;

}
return sb.reverse().toString();

}


public static void main(String[] args) {
for (int i = 1; i < 5000; i++) {
System.out.print(getExcelColumnName(i)+",");
}
}
}

public class ExcelColumns {

	public static String getExcelColumnName(int n){
		if(n < 1) return null;
		StringBuilder sb = new StringBuilder();
		while(n > 0){
			sb.append((char)('A'+(n-1)%26));
			n= (n-1)/26;
			
		}
		return sb.reverse().toString();
		
	}

	
	public static void main(String[] args) {
		for (int i = 1; i < 5000; i++) {
			System.out.print(getExcelColumnName(i)+",");
		}
	}
}