LeetCode 660: Remove 9 Solution

Master LeetCode problem 660 (Remove 9), a hard challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.

660. Remove 9

Hard

Math

Problem Explanation

Explanation:

This problem asks us to remove all occurrences of the digit 9 from the numbers starting from 1 and concatenate them in increasing order. We need to return the n-th integer after removing all occurrences of the digit 9.

To solve the problem, we can use a base-9 number system. By representing the numbers in base-9 and mapping the digit 9 to 10, we can easily calculate the n-th number without having to generate all numbers up to n.

Algorithmic Steps:

Convert the input n to base-9 representation by mapping digit 9 to 10.
Calculate the n-th number in base-9 representation.
Convert the n-th number back to decimal representation.

Time Complexity: O(log(n))
Space Complexity: O(1)

: :

Solution Code

class Solution {
    public int newInteger(int n) {
        return Integer.parseInt(Integer.toString(n, 9));
    }
}

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Frequently Asked Questions

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The time complexity for LeetCode 660 (Remove 9) varies by solution. Check the detailed explanation section for specific complexities in Java, C++, and Python implementations.

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