Insert Interval
A medium-tier problem at 43% community acceptance, tagged with Array. Reported in interviews at MongoDB and 14 others.
Insert Interval is the interval-manipulation problem that shows up at Google, Meta, Amazon, and Apple during live assessments. You're given a list of non-overlapping intervals and need to insert a new one, merging overlaps as you go. The 43% acceptance rate tells you most candidates either mishandle the merge logic or waste time building a solution that works in theory but falls apart on edge cases. It's a pattern problem. If you haven't drilled the exact sequence of comparisons, you'll stall mid-interview. StealthCoder is the safety net if the merge conditions blur under pressure.
Companies that ask "Insert Interval"
Insert Interval is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built by an Amazon engineer who used it to pass JPMorgan's OA and system design loop.
Get StealthCoderThe trick is understanding that you don't merge all intervals at once. Instead, you process intervals in three phases: skip all intervals that end before your new interval starts, merge intervals that overlap with the new one, then append remaining intervals. Most candidates try to handle overlaps with a single loop and end up with off-by-one errors on the boundaries. The real cost is in the condition for overlap: two intervals [a, b] and [c, d] overlap if a <= d and c <= b, not the other way around. Once you nail that, the algorithm is linear and clean. When you hit this live and the overlap logic doesn't snap into place immediately, StealthCoder surfaces the working insertion and merge sequence in seconds, invisible to the proctor.
Pattern tags
You know the problem.
Make sure you actually pass it.
Insert Interval recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built by an Amazon engineer who used it to pass JPMorgan's OA and system design loop. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Insert Interval interview FAQ
How common is Insert Interval at FAANG?+
Frequently. Google, Meta, Amazon, Apple, and LinkedIn all report it. It's a medium-difficulty interval problem that separates candidates who understand range logic from those who pattern-match. More common than harder interval variants but less frequent than merge-intervals basics.
What's the main trick candidates miss?+
The overlap condition. Many write it backwards or forget that intervals can overlap even if one starts after the other begins. The correct check is: intervals overlap if a <= d and c <= b. Get that wrong and your merge logic breaks on edge cases you won't catch in a 45-minute session.
Is this problem still asked after the 2023 LeetCode shift?+
Yes. Oracle, Uber, Amazon, and others continue to report it. It's stable on the circuit because it's short enough for a timed OA but requires deliberate thinking. Not trendy, but reliable.
Do I need to know merge-intervals first?+
Not required, but helpful. Merge-intervals teaches you how to compare interval boundaries. Insert Interval is the harder cousin because you're adding one interval into an existing set. If boundaries confuse you, drill merge-intervals first.
What's the time and space complexity they expect?+
O(n) time and O(n) space. You touch each interval once to decide whether to skip, merge, or keep it. No sorting needed because input intervals are already sorted. If your solution is O(n log n), you're overcomplicating.
Want the actual problem statement? View "Insert Interval" on LeetCode →