The most
https://leetcode.com/problems/4sum/ https://leetcode.com/problems/3sum-closest/ https://leetcode.com/problems/3sum/
https://leetcode.com/problems/find-the-difference-of-two-arrays/ https://leetcode.com/problems/all-nodes-distance-k-in-binary-tree/ https://leetcode.com/problems/minimum-height-trees/ https://leetcode.com/problems/accounts-merge/ https://leetcode.com/problems/evaluate-division/ https://leetcode.com/problems/gas-station/ https://leetcode.com/problems/dota2-senate/ https://leetcode.com/problems/asteroid-collision/ https://leetcode.com/problems/task-scheduler/ https://leetcode.com/problems/next-permutation/ https://leetcode.com/problems/coin-change/
https://leetcode.com/problems/find-the-divisibility-array-of-a-string/
https://leetcode.com/problems/search-a-2d-matrix-ii/
https://leetcode.com/problems/decode-ways/ https://leetcode.com/problems/house-robber-ii/
https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/
https://leetcode.com/problems/interleaving-string/ https://leetcode.com/problems/reorganize-string/ https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-cooldown/ https://leetcode.com/problems/queue-reconstruction-by-height/ https://leetcode.com/problems/find-k-pairs-with-smallest-sums/ https://leetcode.com/problems/top-k-frequent-elements/ https://leetcode.com/problems/partition-equal-subset-sum/ https://leetcode.com/problems/find-k-closest-elements/ https://leetcode.com/problems/number-of-longest-increasing-subsequence/ https://leetcode.com/problems/maximum-swap/ https://leetcode.com/problems/integer-break/ https://leetcode.com/problems/longest-consecutive-sequence/ https://leetcode.com/problems/find-all-duplicates-in-an-array/ https://leetcode.com/problems/reverse-words-in-a-string/ https://leetcode.com/problems/longest-repeating-character-replacement/
//intervals https://leetcode.com/problems/non-overlapping-intervals/ https://leetcode.com/problems/find-right-interval/ https://leetcode.com/problems/insert-interval/ https://leetcode.com/problems/interval-list-intersections/ https://leetcode.com/problems/interval-list-intersections/
https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/ https://leetcode.com/problems/kth-smallest-element-in-a-bst/ https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/ https://leetcode.com/problems/maximum-width-of-binary-tree/ https://leetcode.com/problems/binary-tree-right-side-view/ https://leetcode.com/problems/minimum-path-sum/ https://leetcode.com/problems/balance-a-binary-search-tree/ https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/ https://leetcode.com/problems/validate-binary-search-tree/ https://leetcode.com/problems/merge-two-binary-trees/ https://leetcode.com/problems/maximum-binary-tree/ https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/description/ https://leetcode.com/problems/binary-tree-paths/
https://leetcode.com/problems/integer-to-roman/ https://leetcode.com/problems/minimum-size-subarray-sum/ https://leetcode.com/problems/increasing-triplet-subsequence/ https://leetcode.com/problems/decoded-string-at-index/ https://leetcode.com/problems/bulb-switcher/
https://leetcode.com/problems/is-graph-bipartite/ https://leetcode.com/problems/count-sub-islands/ https://leetcode.com/problems/surrounded-regions/
https://leetcode.com/problems/perfect-squares/ https://leetcode.com/problems/longest-subarray-of-1s-after-deleting-one-element/ https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/ https://leetcode.com/problems/rotate-list/ https://leetcode.com/problems/single-number-iii/ https://leetcode.com/problems/132-pattern/ https://leetcode.com/problems/flatten-a-multilevel-doubly-linked-list/
https://leetcode.com/problems/add-two-numbers-ii/ https://leetcode.com/problems/decode-string/ https://leetcode.com/problems/majority-element-ii/ https://leetcode.com/problems/course-schedule-ii/ https://leetcode.com/problems/course-schedule/ https://leetcode.com/problems/pacific-atlantic-water-flow/ https://leetcode.com/problems/jump-game-iii/ https://leetcode.com/problems/jump-game-ii/ https://leetcode.com/problems/jump-game/ https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/ https://leetcode.com/problems/permutations/ https://leetcode.com/problems/contiguous-array/ https://leetcode.com/problems/design-twitter/ https://leetcode.com/problems/rotate-image/ https://leetcode.com/problems/word-break/
https://leetcode.com/problems/longest-increasing-subsequence/
https://leetcode.com/problems/min-stack/
https://leetcode.com/problems/kth-largest-element-in-an-array/
https://leetcode.com/problems/maximum-binary-tree/ https://leetcode.com/problems/delete-node-in-a-bst/
https://leetcode.com/problems/partition-array-according-to-given-pivot/
https://leetcode.com/problems/lru-cache/ https://leetcode.com/problems/implement-trie-prefix-tree/
//Multi-directional bfs https://leetcode.com/problems/01-matrix/ https://leetcode.com/problems/rotting-oranges/
//Google design question https://leetcode.com/problems/snapshot-array/
//Not clear dfs https://leetcode.com/problems/interleaving-string/
https://leetcode.com/problems/hand-of-straights/
//Design stack https://leetcode.com/problems/design-a-stack-with-increment-operation/
https://leetcode.com/problems/can-place-flowers/ https://leetcode.com/problems/fruit-into-baskets/
//backtrack https://leetcode.com/problems/combinations/ https://leetcode.com/problems/combination-sum/ https://leetcode.com/problems/coin-change/ //dp https://leetcode.com/problems/palindrome-partitioning/ https://leetcode.com/problems/target-sum/ https://leetcode.com/problems/combination-sum-ii/ https://leetcode.com/problems/combination-sum-iii/ https://leetcode.com/problems/partition-to-k-equal-sum-subsets/ https://leetcode.com/problems/split-a-string-into-the-max-number-of-unique-substrings/ https://leetcode.com/problems/subsets-ii/ https://leetcode.com/problems/letter-combinations-of-a-phone-number/
//bin search https://leetcode.com/problems/koko-eating-bananas/ https://leetcode.com/problems/find-k-closest-elements/ https://leetcode.com/problems/search-a-2d-matrix/ https://leetcode.com/problems/find-peak-element/ https://leetcode.com/problems/single-element-in-a-sorted-array/ https://leetcode.com/problems/capacity-to-ship-packages-within-d-days/ https://leetcode.com/problems/peak-index-in-a-mountain-array/ https://leetcode.com/problems/find-positive-integer-solution-for-a-given-equation/
//easy but medium, balance https://leetcode.com/problems/fair-candy-swap/
//List https://leetcode.com/problems/linked-list-cycle-ii/ https://leetcode.com/problems/split-linked-list-in-parts/ https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/ https://leetcode.com/problems/partition-list/ https://leetcode.com/problems/swap-nodes-in-pairs/ https://leetcode.com/problems/reverse-linked-list-ii/ https://leetcode.com/problems/odd-even-linked-list/
//Tree https://leetcode.com/problems/deepest-leaves-sum/ https://leetcode.com/problems/count-nodes-equal-to-average-of-subtree/
//Matrix https://leetcode.com/problems/sort-the-matrix-diagonally/
//DP https://leetcode.com/problems/min-cost-climbing-stairs/ https://leetcode.com/problems/unique-paths-ii/ https://leetcode.com/problems/unique-paths/
//Two pointers, bin search https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/ https://leetcode.com/problems/number-of-subsequences-that-satisfy-the-given-sum-condition/
//Sliding window https://leetcode.com/problems/max-consecutive-ones-iii/ https://leetcode.com/problems/longest-subarray-of-1s-after-deleting-one-element/
// Divide and Conquer https://leetcode.com/problems/maximum-sum-circular-subarray/
https://leetcode.com/problems/container-with-most-water/ https://leetcode.com/problems/path-sum-ii/ https://leetcode.com/problems/path-sum-iii/
https://leetcode.com/problems/find-the-longest-balanced-substring-of-a-binary-string/
//priority queue https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/ https://leetcode.com/problems/kth-largest-element-in-an-array/ https://leetcode.com/problems/reorganize-string/ Queue maxHeap = new PriorityQueue<>((a, b) -> frequency.get(b) - frequency.get(a)); https://leetcode.com/problems/find-k-pairs-with-smallest-sums/ https://leetcode.com/problems/k-closest-points-to-origin/ https://leetcode.com/problems/sort-characters-by-frequency/
//hashmap sliding window two pointers https://leetcode.com/problems/permutation-in-string/
//good to know https://leetcode.com/problems/generate-parentheses/ https://leetcode.com/problems/find-the-difference/ https://leetcode.com/problems/ransom-note/ https://leetcode.com/problems/set-matrix-zeroes/ https://leetcode.com/problems/word-pattern/
//palindrome https://leetcode.com/problems/palindromic-substrings/ https://leetcode.com/problems/longest-palindromic-substring/
//prefix https://leetcode.com/problems/product-of-array-except-self/ https://leetcode.com/problems/minimum-number-of-operations-to-move-all-balls-to-each-box/
//medium graph https://leetcode.com/problems/number-of-provinces/
//medium hashmap https://leetcode.com/problems/maximum-number-of-vowels-in-a-substring-of-given-length/
//not clear https://leetcode.com/problems/h-index/ //sort https://leetcode.com/problems/determine-if-two-strings-are-close/ //hashmap https://leetcode.com/problems/maximum-number-of-vowels-in-a-substring-of-given-length/
//great easy https://leetcode.com/problems/sign-of-the-product-of-an-array/ https://leetcode.com/problems/find-the-difference-of-two-arrays/ https://leetcode.com/problems/add-digits/ https://leetcode.com/problems/average-salary-excluding-the-minimum-and-maximum-salary/
//todo todo todo //todo todo //FOREIGN_SOLUTION //NOT_OPTIMAL //TOP
//nov oct top https://leetcode.com/problems/check-if-a-parentheses-string-can-be-valid/ https://leetcode.com/problems/find-the-winner-of-the-circular-game/ https://leetcode.com/problems/binary-tree-pruning/ https://leetcode.com/problems/count-good-nodes-in-binary-tree/ https://leetcode.com/problems/rearrange-array-elements-by-sign/