Two Pointers Removing Sorted Duplicates
An array walkthrough showing a slow pointer i and fast pointer j scanning a sorted list to remove duplicates in place. The animation highlights how j compares neighboring values while i marks where the next valid element should be written, illustrating the core two-pointer compaction pattern used in array deduplication problems. Useful for students studying in-place array algorithms and common coding-interview techniques like the 'remove duplicates' family of problems.
16:9 · Preview before teaching · automatic layout checks do not establish subject accuracy
The prompt that made it
class Solution { public int removeDuplicates(int[] nums) { int i=0; for(int j=0;j<nums.length;j++){ if(nums[j] == nums[i] && nums[j]==nums[j+1]){ continue; }else{ nums[i]=nums[j-1]; i++; }if(j==nums.length-1){ nums[i]=nums[j]; } } return i; } }
Make the next one in this series
- Animate the correct version allowing at most two duplicates per value
- Compare in-place array compaction versus using extra memory for deduplication
- Show how the same two-pointer pattern solves partitioning an array around a pivot
