The Accountant - Google Top Interview Questions

Problem Statement :

Spreadsheets often use this alphabetical encoding for its columns: "A", "B", "C", ..., "AA", "AB", "AC", ..., "ZZ", "AAA", "AAB", "AAC", ....

Given a column number n, return its alphabetical column id. For example, given 1, return "A". Given 27, return "AA".


1 ≤ n < 2 ** 31

Example 1


n = 1



Example 2


n = 2


Example 3


n = 26



Example 4


n = 27



Solution :


                        Solution in C++ :

string solve(int n) {
    string result;
    while (n > 0) {
        // Since in code 'A' + 25 = 'Z'

        // Get the remainder to identify
        // the current character to be
        // added to the column number
        int curr = n % 26;

        // Divide by 26 to process the
        // next character
        n = n / 26;

        // Update the result with the
        // current character
        result.push_back(curr + 'A');

    // Since we are adding the most
    // significant character to the end
    // of the string, reverse it before
    // returning
    reverse(result.begin(), result.end());

    return result;

                        Solution in Java :

import java.util.*;

class Solution {
    public String solve(int A) {
        String s = "";
        int counter = 0;
        while (A > 0) {
            counter = (A - 1) % 26;
            char a = (char) ('A' + counter);
            s = a + s;
            A = (A - 1) / 26;
        return s;

                        Solution in Python : 
class Solution:
    def solve(self, n):

        ans = ""

        # because we have 1 based indexing
        # we need to scale 1-27 to 0-26 each time
        # so, we use n-1
        while n >= 1:
            ans += chr((n - 1) % 26 + ord("A"))
            n = (n - 1) // 26

        return ans[::-1]

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