Answer: BETTER Hiring | Off-Campus OA (2025) | Find All Numbers Disappeared in an Array

Approach Since every number lies in the range 1 to n, use each value as an index. Traverse the array: For every number, mark its corresponding index as visited by making the value at that index negative. Traverse the array again: If any value is still positive, its index + 1 was never visited. Add it to the answer. This approach avoids using any extra array. Strategy Use the input array itself for marking visited numbers. Convert values to negative ...