Amazon India Fresher Hiring 2026

Use a hash map to count each character in one pass, then scan the string again and return the first character with count 1. Time O(n), space O(1) for a fixed alphabet. Mention handling of empty strings and case-sensitivity as edge cases.

Floyd’s Tortoise & Hare: move a slow pointer by 1 and a fast pointer by 2. If they ever meet, there is a cycle; if fast hits null, there isn’t. O(n) time, O(1) space. Be ready to extend it to find the cycle’s start node.

Treat the grid as a graph and run DFS/BFS from every unvisited “1”, sinking the whole connected component each time; increment a counter per new component. O(rows×cols). Clarify whether diagonal connections count.

Bottom-up DP: dp[x] = min(dp[x − coin] + 1) over all coins. Initialise dp[0]=0, rest to infinity. O(amount×coins). Explain why greedy fails for arbitrary denominations.

A process is an independent program with its own memory space; a thread is a lightweight unit of execution that shares its process’s memory. Threads are cheaper to create and communicate, but need synchronization to avoid race conditions.

DELETE removes selected rows and can be rolled back (DML, fires triggers). TRUNCATE removes all rows fast without logging each row and resets identity (DDL). DROP removes the entire table structure. Order of destructiveness: DELETE < TRUNCATE < DROP.

Atomicity (all-or-nothing transactions), Consistency (valid state to valid state), Isolation (concurrent transactions don’t corrupt each other), Durability (committed data survives crashes). They guarantee reliable database transactions.

Encapsulation (bundle data + behaviour, hide internals), Abstraction (expose only what matters), Inheritance (reuse via parent–child), Polymorphism (one interface, many forms via overriding/overloading). Give a quick real example for each.

Use STAR: Situation, Task, Action, Result. Pick a real example where you spotted a gap nobody owned, stepped up, drove it to done, and quantify the impact. Maps to “Ownership” and “Bias for Action”.

Show “Have Backbone; Disagree and Commit”: you voiced a reasoned, data-backed disagreement respectfully, then — once a decision was made — committed fully and helped execute it. End with the outcome and what you learned.

Choose a genuine failure, own your part without blaming others, explain the root cause you found (Dive Deep), the fix, and how you changed your approach afterwards (Learn and Be Curious). Authenticity beats a “humble-brag”.

Be specific: scale of impact, the builder/ownership culture, the Leadership Principles, and a product or AWS service you genuinely admire. Avoid generic “big company / good package” answers — tie it to how you like to work.

Show growth ambition grounded in the role: becoming a strong, independent engineer, owning larger systems, mentoring juniors, and deepening expertise — framed around delivering customer impact, not just titles.

For freshers, say you’re open to Amazon’s standard SDE-1 structure and trust it’s fair and competitive; you can note you’ve researched the market. Keep it collaborative, not a hard negotiation at this stage.