https://leetcode.com/problems/merge-in-between-linked-lists/description/

Replace a segment in a LinkedList #medium

https://leetcode.com/problems/reverse-linked-list/description/

Reverse a Linked List #easy

https://leetcode.com/problems/palindrome-linked-list/description/

Is Linked List a palindrome #easy

https://leetcode.com/problems/reorder-list/description/

Reorder Linked List 1->2->3->4->5 -> 1->5->2->4->3 #medium

https://leetcode.com/problems/find-the-duplicate-number/description/

Duplicate single number in 1..n array, no extra memory #medium

https://leetcode.com/problems/find-all-duplicates-in-an-array/description/

All duplicate numbers of 1..n using O(1) memory #medium

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

First number 1.. not presented in the array, O(1) space #hard

https://leetcode.com/problems/subarray-product-less-than-k/description/

Subarrays count with product less than k #medium

https://leetcode.com/problems/length-of-longest-subarray-with-at-most-k-frequency/description

Max subarray length with frequencies <= k #medium

https://leetcode.com/problems/count-subarrays-where-max-element-appears-at-least-k-times/description/

Count subarrays with at least k array max in #medium

https://leetcode.com/problems/count-subarrays-with-fixed-bounds/description/

Count subarrays of range minK..maxK #hard

https://leetcode.com/problems/length-of-last-word/description/

Last word length #easy

https://leetcode.com/problems/isomorphic-strings/description/

Can map chars from one string to another? #easy

https://leetcode.com/problems/word-search/description/

Does grid have a word path? #medium

https://leetcode.com/problems/maximum-nesting-depth-of-the-parentheses/description/

Max nested parenthesis #easy

https://leetcode.com/problems/make-the-string-great/description/

Remove lowercase-uppercase pairs #easy

https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses/description/

Remove minimum to make parenthesis valid #medium

https://leetcode.com/problems/valid-parenthesis-string/description/

Are parenthesis valid with wildcard? #medium

https://leetcode.com/problems/number-of-students-unable-to-eat-lunch/description/

First sandwitch not eaten by any while popped from a queue #easy