Remove 9

This page explains Java solution to problem Remove 9 using Bit manipulation.

Problem Statement

Start from integer 1, remove any integer that contains 9 such as 9, 19, 29...

So now, you will have a new integer sequence: 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, ...

Given a positive integer n, you need to return the n-th integer after removing. Note that 1 will be the first integer.

Input: n = 9
Output: 10

Solution

package com.vc.hard;

class Remove9 {
    public int newInteger(int n) {
        //Converting number to base 9 number
        String baseNine = Integer.toString(n, 9);
        return Integer.parseInt(baseNine);
    }
}

Time Complexity

O(1)

Space Complexity

O(1)