Add One to an Integer Stored as Digits Without ArrayList
Last updated: August 10, 2026
Quick Overview
The question asks the candidate to implement a function that adds one to an integer represented as an array of its digits, without using an ArrayList.
Oracle
August 10, 20261
0
15 solved
The question asks the candidate to implement a function that adds one to an integer represented as an array of its digits, without using an ArrayList.
This question is typically asked in the onsite interview round for backend engineering roles at Oracle. The interviewer is evaluating the candidate's problem-solving skills, ability to manipulate data structures, and understanding of algorithmic complexity. It also tests the candidate's coding proficiency and familiarity with basic data types in Java or similar languages.
What the Interviewer Expects
- Clearly outline the approach to solving the problem.
- Provide a correct and efficient algorithm to add one to the integer.
- Discuss the time and space complexity of the solution.
- Handle edge cases, such as carrying over digits.
- Write clean and maintainable code.
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- How would you handle very large integers that exceed standard data types?
- Can you explain how you would optimize your solution further?
- What would you change if the input was a string instead of an array?
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Practice DSA ProblemsSample Answer
Approach
To solve the problem of adding one to an integer represented as an array of its digits, we will iterate through the array from the last digit to the first. We will handle the carry that results from a...
Algorithm
Here is a simple implementation in Python:
def add_one(digits):
n = len(digits)
for i in range(n - 1, -1, -1):
if digits[i] < 9:
digits[i] += 1
retur...
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