LINE Coding Interview Questions
25 LINE coding interview problems with full optimal solutions — 12 easy, 10 medium, 3 hard. Every problem ships with multiple approaches (brute-force first, then the optimal), complexity tables for each, company-specific tips on what an LINE interviewer values, and a FAQ section.
Showing 12 problems of 25
- #1easyfoundational
1. Two Sum
Find two indices in an array whose values sum to a target — LINE warms up new grads with this before chat-server design.
- #2easyfoundational
2. Valid Parentheses
Validate a string of brackets — LINE uses it to check whether you reach for a stack instantly when a chat message body has nested formatting.
- #3easyfoundational
3. Merge Two Sorted Lists
Merge two sorted linked lists into one sorted list — LINE uses this as a proxy for merging two ordered chat timelines.
- #4easyfoundational
4. Remove Duplicates from Sorted Array
Dedup a sorted array in place — LINE uses this when discussing how to compact dedup'd message IDs in an offline outbox.
- #5easyfoundational
5. Remove Element
Remove all instances of a value from an array in place — LINE uses this as a stand-in for purging muted-user messages from a feed buffer.
- #6easyfoundational
6. Search Insert Position
Find where to insert a value in a sorted array — LINE uses this to gauge whether you spot binary search opportunities in sorted message-timestamp lookups.
- #7easyfoundational
7. Same Tree
Decide if two binary trees are structurally identical and have equal values at every node — LINE uses this to test recursion clarity before moving into chat-tree replication design.
- #8easyfoundational
8. Maximum Depth of Binary Tree
Return the maximum depth of a binary tree — LINE asks this to gauge whether you instinctively reach for recursion before BFS when the input is a tree.
- #9easyfoundational
9. Pascal's Triangle
Generate the first n rows of Pascal's triangle — LINE uses this to check that you can build up tabular data without off-by-one errors before moving into sticker-pack pagination.
- #10easyfoundational
10. Best Time to Buy and Sell Stock
Find the maximum profit from one buy and one sell — LINE uses this to see if you spot the running-minimum trick, the same primitive behind their payment-reconciliation min-balance scan.
- #11easyfoundational
11. Valid Palindrome
Determine if a string is a palindrome when ignoring non-alphanumeric characters and case — LINE uses this to test two-pointer fundamentals before any chat-search problem.
- #12easyfoundational
12. Single Number
Find the element that appears exactly once when every other element appears twice — LINE uses this to test whether you reach for XOR before a hash map, the same shape as deduping read-receipt acks.