All Problems

Codewars:

Easy Problems

• https://www.codewars.com/kata/5ce9c1000bab0b001134f5af

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Leetcode

Easy Problems

• https://leetcode.com/problems/length-of-last-word/
• https://leetcode.com/problems/fizz-buzz/description/
• https://leetcode.com/problems/binary-search/
• XOR: https://leetcode.com/problems/single-number/description/
• https://leetcode.com/problems/count-subarrays-of-length-three-with-a-condition/description/?envType=daily-question&envId=2025-04-27
• https://leetcode.com/problems/palindrome-number/description/
• Log(n^2) https://leetcode.com/problems/two-sum/description/
• HashMap: https://leetcode.com/problems/two-sum/description/
• Two Pointers: https://leetcode.com/problems/move-zeroes/description/
• One Pointer: https://leetcode.com/problems/best-time-to-buy-and-sell-stock/description/
• https://leetcode.com/problems/ransom-note/
• https://leetcode.com/problems/contains-duplicate/
• https://leetcode.com/problems/contains-duplicate-ii/description/
• https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/description/
• https://leetcode.com/problems/three-consecutive-odds/description/?envType=daily-question&envId=2025-05-11
• String Problem: https://leetcode.com/problems/is-subsequence/description/
• https://leetcode.com/problems/remove-duplicates-from-sorted-array/description/
• https://leetcode.com/problems/valid-palindrome/
• https://leetcode.com/problems/merge-sorted-array/
• https://leetcode.com/problems/valid-parentheses/description/

Medium Problems

• https://leetcode.com/problems/search-in-rotated-sorted-array/description/
• https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/description/
• Factorial Trailing Zeroes: https://leetcode.com/problems/factorial-trailing-zeroes/submissions/
• https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/
• https://leetcode.com/problems/rotate-array/description/
• https://leetcode.com/problems/jump-game/description/
• https://leetcode.com/problems/product-of-array-except-self/
• Hash Table: https://leetcode.com/problems/sequential-digits/description/
• Hash Table: https://leetcode.com/problems/find-all-duplicates-in-an-array/
• https://leetcode.com/problems/minimum-equal-sum-of-two-arrays-after-replacing-zeros/description/?envType=daily-question&envId=2025-05-10
• Bad Question : I don't recommend to solve: https://leetcode.com/problems/next-permutation/description/
• https://leetcode.com/problems/subarray-product-less-than-k/description/
• https://leetcode.com/problems/k-diff-pairs-in-an-array/description/
• Two Pointers: with new idea: https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/description/
• https://leetcode.com/problems/sort-colors/description/
• Medium but Very Hard: https://leetcode.com/problems/3sum/

Hard Problems

• https://leetcode.com/problems/first-missing-positive/description/

Topics

• XOR
• Binary Search
• Rotated Sorted Array
• Palindrome Number
• Factorial
• Hash Map (DS)
• 2 Pointers (Two Pointers)
  • left and right pointers
  • Sliding window
• Prefix sum &&& Suffix sum
• Prefix product &&& Suffix product
• Hash Table (DS)
• Mark Indices --> By negative value
• Sliding Window
• Stack (DS)

Algorithms

• Greedy Algorithm

Notes:

• Map In Dart (Hash Map ---- Linked Hash Map ---- Splay Tree Map)

• Hash Map (Not Ordered) -- Hash Table (Ordered)

• Hash Table

  A Hash table is defined as a data structure used to insert, look up, and remove key-value pairs quickly. It operates on the hashing concept, where each key is translated by a hash function into a distinct index in an array. The index functions as a storage location for the matching value. In simple words, it maps the keys with the value.

• Find Sum of 2 Numbers in sorted List

  1. Brute Force (Bad)
  2. Two Pointers