Amazon Software Developer Intern Interview Questions and Answers

2 leetcode easy problems, arrays and strings.

Q1. Minimum window substring
Ans. 
Find the smallest substring in a string that contains all characters of another string.
• Use two pointers to maintain a sliding window over the string.

• Count characters in the target string using a hash map.

• Expand the window by moving the right pointer and contract it by moving the left pointer.

• Example: For s = 'ADOBECODEBANC' and t = 'ABC', the result is 'BANC'.

• Keep track of the minimum length and starting index of valid...read more
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Q2. Minimum sum of subarray
Ans. 
Find the minimum sum of a subarray within an array of integers.
• Iterate through the array and keep track of the current sum of subarray

• Update the minimum sum if a smaller sum is found

• Consider using Kadane's algorithm for an efficient solution
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Q1. BFS of graph
Ans. 
BFS (Breadth-First Search) is an algorithm for traversing or searching tree or graph data structures level by level.
• Level Order Traversal: BFS explores all neighbors at the present depth prior to moving on to nodes at the next depth level.

• Queue Data Structure: BFS uses a queue to keep track of nodes to be explored, ensuring nodes are processed in the order they are discovered.

• Shortest Path: In unweighted graphs, BFS ca...read more
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Q2. Behavioural questions
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It had very basic dsa problem I don't not remember the exact question. It was based on array manipulation.

Q1. Rotten oranges graph question
Ans. 
The Rotten Oranges problem involves determining the time taken for all oranges to rot in a grid.
• Model the grid as a graph where each cell represents an orange.

• Use BFS to simulate the rotting process, starting from all initially rotten oranges.

• Count the minutes taken for all reachable fresh oranges to rot.

• Example: In a 2D grid, rotten oranges spread to adjacent fresh oranges every minute.
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Q2. One standard dp question which could be solved in 4-5 line of code
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Basic aptitude and data structures along with some personality based questions

Q1. Coding question on sliding window algorithm
Ans. 
The sliding window algorithm efficiently solves problems involving contiguous subarrays or substrings.
• Used to find maximum/minimum in a subarray of fixed size. Example: max sum of any 3 consecutive elements.

• Helps in counting distinct elements in a substring. Example: count of unique characters in 'abcabc'.

• Can be applied to problems like longest substring without repeating characters. Example: 'abcabcbb' -> 'abc'.

• Use...read more
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Q2. Standard leetcode medium problem on binary search
Ans. 
Binary search is an efficient algorithm for finding an item from a sorted list of items.
• Binary search works on sorted arrays. Example: [1, 2, 3, 4, 5].

• It divides the search interval in half. If the target is less than the middle element, search the left half.

• Time complexity is O(log n), making it faster than linear search (O(n)).

• Example: To find 3 in [1, 2, 3, 4, 5], check middle (3), found it immediately.

• If the target...read more
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LC Medium - 2 questions

Q1. LC Medium on two-pointers
Ans. 
Two-pointer technique is used to solve problems involving arrays or linked lists by using two pointers to traverse the data structure.
• Start with two pointers at different positions in the array or linked list

• Move the pointers based on the problem requirements (e.g. one pointer moves faster than the other)

• Commonly used in problems like finding a pair of elements that sum up to a target value
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Q2. LC Medium-Hard on DP
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Q1. Sliding window question
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Q2. Trees medium level
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