https://leetcode.com/problems/maximal-rectangle/description/

Max 1-only area in a 0-1 matrix #hard

https://leetcode.com/problems/sum-of-left-leaves/description/

Left-leaf sum in a Binary Tree #easy

https://leetcode.com/problems/sum-root-to-leaf-numbers/description/

Sum root-leaf numbers in a Binary Tree #medium

https://leetcode.com/problems/add-one-row-to-tree/description/

Insert nodes at the depth of the Binary Tree #medium

https://leetcode.com/problems/smallest-string-starting-from-leaf/description/

Smallest string from leaf to root in a Binary Tree #medium

https://leetcode.com/problems/island-perimeter/description/

Perimeter of 1's islands in 01-matrix #easy

https://leetcode.com/problems/number-of-islands/description/

Count 1-islands in 0-1 a 2D matrix #medium

https://leetcode.com/problems/find-all-groups-of-farmland/description/

Count 1-rectangles in 0-1 2D matrix #medium

https://leetcode.com/problems/find-if-path-exists-in-graph/description/

Are source and destination connected in graph? #easy

https://leetcode.com/problems/minimum-height-trees/description/


Center of an acyclic graph #medium #graph #toposort

https://leetcode.com/problems/n-th-tribonacci-number/description/

`n`th Tribonacci number f(n + 3) = f(n) + f(n + 1) + f(n + 2) #easy

https://leetcode.com/problems/longest-ideal-subsequence/description/

Max length of less than k adjucent subsequence #medium #dynamic_programming

https://leetcode.com/problems/minimum-falling-path-sum-ii/description/

Min non-direct path top down in a 2D matrix #hard #dynamic_programming

https://leetcode.com/problems/freedom-trail/description/

Min steps to produce key by rotating ring #hard #dynamic_programming #recursion #hash_map

https://leetcode.com/problems/sum-of-distances-in-tree/description/

Sums of paths to each leafs in a tree #hard #dfs

https://leetcode.com/problems/minimum-number-of-operations-to-make-array-xor-equal-to-k/description/

Bit diff between k and nums xor #medium #bit_manipulation

https://leetcode.com/problems/number-of-wonderful-substrings/description/

Count substrings with at most one odd frequency #medium #bit_manipulation

https://leetcode.com/problems/reverse-prefix-of-word/description/

Reverse [..ch] prefix in string #easy

https://leetcode.com/problems/largest-positive-integer-that-exists-with-its-negative/description/

Max number that have its negative in array #easy #two_pointers