Apple

18 problems asked at Apple.

Easy (6)

Implement Queue using Stacks (LeetCode 232)

Stack, Queue

Stack using Queue (LeetCode 225)

Stack, Queue

Top K Frequent Elements (Leetcode 347)

Arrays, Hashing, Heap...

Two Sum (Leetcode 1)

Two Pointers, Arrays

Valid Anagram (leetcode 242)

Arrays, Hashing, Strings

Valid Parentheses (Leetcode 20)

Stack, Strings

Medium (5)

Find the Smallest Divisor Given a Threshold

Searching

Gas Station (Leetcode 134)

Arrays, Greedy, Prefix Sum

Group Anagrams (Leetcode 49)

Arrays, Strings, Sorting...

Longest Substring Without Repeating Characters (leetcode 3)

Sliding Window, Strings, Hashing

Min Stack (Leetcode 155)

Stack

Hard (5)

Largest Rectangle in Histogram (leetcode 84)

Arrays, Stack

Next Permutation (Leetcode 31)

Arrays, Greedy, Two Pointers

Postfix to Infix & Evaluation of Postfix (Leetcode 150)

Stack

Repeating Element (Cycle + Expected Sum appr.)

Arrays, Two Pointers, Linked Lists

Trapping Rain Water (LC 42)

Two Pointers, Prefix and Suffix Arrays, Stack

Not Specified (2)

Best Time to Buy and Sell Stock

Arrays, DP

Container With Most Water

Two Pointers