https://leetcode.com/problems/magic-squares-in-grid/description/

Count 9x9 1..9 equal row col diag sum subgrids #medium

https://leetcode.com/problems/regions-cut-by-slashes/description/

Count islands divided by '\' and '/' in 2D matrix #medium #union-find

https://leetcode.com/problems/minimum-number-of-days-to-disconnect-island/description/

Min changes 1 to 0 to disconnect islands #hard #union-find

https://leetcode.com/problems/kth-largest-element-in-a-stream/description/

`k`th largest in a stream of values #easy #heap

https://leetcode.com/problems/combination-sum-ii/description/

Unique target sum subsequencies #medium #backtracking

https://leetcode.com/problems/find-k-th-smallest-pair-distance/description/

`k`th smallest pairs diff in array #hard #binary_search #two_pointers

https://leetcode.com/problems/lemonade-change/description/

Simulate money exchange #easy #simulation

https://leetcode.com/problems/maximum-distance-in-arrays/description/

Max diff between the arrays #medium

https://leetcode.com/problems/maximum-number-of-points-with-cost/description/

Max top-down path sum with column diff in 2D matrix #medium #dynamic_programming

https://leetcode.com/problems/ugly-number-ii/description/

`n`th number with only [1,2,3,5] multipliers #medium #heap

https://leetcode.com/problems/2-keys-keyboard/description/

Min copy-pastes to make n A's from one #medium #dynamic_programming #math

https://leetcode.com/problems/stone-game-ii/description/

Max Alice price taking 1..2m piles optimally with Bob #medium #dynamic_programming

https://leetcode.com/problems/strange-printer/description/

Minimum continuous replacements to make a string #hard #dynamic_programming

https://leetcode.com/problems/number-complement/description/

Invert bits: 101 becomes 010 #easy #bit_manipulation

https://leetcode.com/problems/fraction-addition-and-subtraction/description/

Eval string of fractions sum #medium #math

https://leetcode.com/problems/find-the-closest-palindrome/description/

Closest palindrome number #hard #math

https://leetcode.com/problems/binary-tree-postorder-traversal/description/

Postorder tree traversal #easy #binary_tree

https://leetcode.com/problems/n-ary-tree-postorder-traversal/description/

Postorder tree traversal #easy #tree

https://leetcode.com/problems/path-with-maximum-probability/description/

Max path in a weighted graph #medium #graph

https://leetcode.com/problems/count-sub-islands/description/

Count islands intersecting in both 2D grids #medium #dfs

https://leetcode.com/problems/most-stones-removed-with-same-row-or-column/description/

Count islands of intersecting x and y #medium #union-find