https://leetcode.com/problems/maximum-matrix-sum/description/


Max sum of 2D matrix after multiply by -1 adjacent cells #medium

https://leetcode.com/problems/sliding-puzzle/description/


Steps to solve slide puzzle #hard #bfs

https://leetcode.com/problems/find-champion-ii/description/


Root of the graph #medium

https://leetcode.com/problems/shortest-distance-after-road-addition-queries-i/description/


Query shortest paths after adding new edges #medium #bfs

https://leetcode.com/problems/minimum-obstacle-removal-to-reach-corner/description/


Min removals to travel first-last in 2D grid #hard #bfs #dijkstra

https://leetcode.com/problems/minimum-time-to-visit-a-cell-in-a-grid/description/


Min time start-end 4-d travel in 2D matrix with waiting #hard #dijkstra

https://leetcode.com/problems/valid-arrangement-of-pairs/description/


Hierholzer's algorithm #hard #graph

https://leetcode.com/problems/check-if-n-and-its-double-exist/description/

Any i != j && a[i] = 2 * a[j] #easy

https://leetcode.com/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence/description/


Position of the prefix #easy

this is a personal

https://leetcode.com/problems/adding-spaces-to-a-string/description/


Insert spaces into string #medium

https://leetcode.com/problems/make-string-a-subsequence-using-cyclic-increments/description/


Increase some chars once to make a subsequence #medium

https://leetcode.com/problems/move-pieces-to-obtain-a-string/description/


Move L left and R right to match strings #medium

https://leetcode.com/problems/maximum-number-of-integers-to-choose-from-a-range-i/description/


Sum 1..n excluding banned until maxSum #medium

https://leetcode.com/problems/minimum-limit-of-balls-in-a-bag/description/


Max number after at most maxOperations of splitting #medium #binary_search

https://leetcode.com/problems/two-best-non-overlapping-events/description/

Max two non-overlapping intervals #medium #binary_search

https://leetcode.com/problems/special-array-ii/description/

Queries is all adjucents parity differ [i..j] #medium #two_pointers

https://leetcode.com/problems/find-longest-special-substring-that-occurs-thrice-i/description/

Max same-char 3-windows length #medium #sliding_window

https://leetcode.com/problems/maximum-beauty-of-an-array-after-applying-operation/description/


Max equal nums after adjusting to [-k..+k] #medium #binary_search #line_sweep

https://leetcode.com/problems/take-gifts-from-the-richest-pile/description/

Sum after k-Sqrt of tops in array #easy