Arrays · Coding problem
Remove Duplicates from Sorted Array
A free coding problem from the In-Place Manipulation skill. Read it here, then solve it in the app in Java or Python.
- Easy
- Coding problem
- Free
- Java and Python
The problem
nums is sorted, so equal values sit next to each other. Squeeze out the repeats in place, so the first k slots of nums hold each distinct value once, in their original order, and report k. Whatever is left after index k doesn't matter.
Output format
Print the first k values, space-separated.
Example
Input: nums = [-3, -3, 0, 2, 2, 2, 9]
Output: -3 0 2 9
Here k = 4.
Solve it in a single pass with O(1) extra space, without allocating a second array.
Constraints
1 <= nums.length <= 2 * 10^5-100 <= nums[i] <= 100numsis sorted ascending
How it's graded
- Run checks your code against the examples. Submit also runs a hidden suite in four groups - basic cases, edge cases, random inputs and performance tests at the size limit - and shows which groups pass, never the hidden inputs.
- Stuck? Hints come in four steps, from a nudge to a code skeleton, each costing part of the points.
- Once you pass, you see the approaches from brute force to optimal, and where your solution lands among them.
More problems in In-Place Manipulation
- Move ZeroesFree
Solve it Remove Duplicates from Sorted Array free
No card needed. Lessons, practice questions and easy problems are free forever.
Free plan, no card · 7-day Pro trial · Cancel anytime