LeetCode 07xx
LeetCode practice notes for problems 700 through 799, including Search for a target value in a binary search tree and return the subtree rooted at the matching node.
LeetCode 07xx
| # | Title | Difficulty | Description |
|---|---|---|---|
| 700 | LeetCode 700: Search in a Binary Search Tree | Easy | Search for a target value in a binary search tree and return the subtree rooted at the matching node. |
| 701 | LeetCode 701: Insert into a Binary Search Tree | Medium | A clear explanation of inserting a value into a binary search tree using recursive and iterative traversal. |
| 702 | LeetCode 702: Search in a Sorted Array of Unknown Size | Medium | A clear explanation of searching in a sorted array when the array length is hidden behind an ArrayReader interface. |
| 703 | LeetCode 703: Kth Largest Element in a Stream | Easy | A clear explanation of maintaining the kth largest element in a stream using a fixed-size min heap. |
| 704 | LeetCode 704: Binary Search | Easy | A clear explanation of searching for a target in a sorted array using binary search. |
| 705 | LeetCode 705: Design HashSet | Easy | A clear explanation of designing a hash set without using built-in hash table libraries. |
| 706 | LeetCode 706: Design HashMap | Easy | A clear explanation of designing a hash map without using built-in hash table libraries. |
| 707 | LeetCode 707: Design Linked List | Medium | A clear explanation of implementing a linked list from scratch using nodes, a dummy head, and a size counter. |
| 708 | LeetCode 708: Insert into a Sorted Circular Linked List | Medium | A clear explanation of inserting a value into a sorted circular linked list while preserving the circular sorted order. |
| 709 | LeetCode 709: To Lower Case | Easy | A clear explanation of converting uppercase ASCII letters to lowercase by scanning the string once. |
| 710 | LeetCode 710: Random Pick with Blacklist | Hard | A clear explanation of selecting a uniformly random integer while excluding blacklisted values using remapping and hashing. |
| 711 | LeetCode 711: Number of Distinct Islands II | Hard | A clear explanation of counting distinct island shapes under rotation and reflection using normalization and geometric transformations. |
| 712 | LeetCode 712: Minimum ASCII Delete Sum for Two Strings | Medium | A clear explanation of using dynamic programming to minimize the ASCII cost of deletions needed to make two strings equal. |
| 713 | LeetCode 713: Subarray Product Less Than K | Medium | A clear explanation of counting contiguous subarrays whose product is less than k using a sliding window. |
| 714 | LeetCode 714: Best Time to Buy and Sell Stock with Transaction Fee | Medium | A clear explanation of maximizing stock trading profit with unlimited transactions and a fixed transaction fee using dynamic programming. |
| 715 | LeetCode 715: Range Module | Hard | A clear explanation of designing a range module that can add, query, and remove half-open intervals. |
| 716 | LeetCode 716: Max Stack | Hard | A clear explanation of designing a stack that supports push, pop, top, peekMax, and popMax. |
| 717 | LeetCode 717: 1-bit and 2-bit Characters | Easy | A clear explanation of determining whether the last character must be a one-bit character using greedy parsing. |
| 718 | LeetCode 718: Maximum Length of Repeated Subarray | Medium | A clear explanation of finding the longest common contiguous subarray using dynamic programming. |
| 719 | LeetCode 719: Find K-th Smallest Pair Distance | Hard | A clear explanation of finding the kth smallest pair distance using sorting, binary search on the answer, and a two-pointer count. |
| 720 | LeetCode 720: Longest Word in Dictionary | Easy | A clear explanation of finding the longest buildable word using sorting and a hash set. |
| 721 | LeetCode 721: Accounts Merge | Medium | A clear explanation of merging accounts that share emails using union find and sorted email groups. |
| 722 | LeetCode 722: Remove Comments | Medium | A clear explanation of removing line comments and block comments from source code using a state machine. |
| 723 | LeetCode 723: Candy Crush | Medium | A clear explanation of restoring a Candy Crush board to a stable state using repeated marking, crushing, and gravity simulation. |
| 724 | LeetCode 724: Find Pivot Index | Easy | A clear explanation of finding the leftmost pivot index using prefix sums and a running left sum. |
| 725 | LeetCode 725: Split Linked List in Parts | Medium | A clear explanation of splitting a linked list into k consecutive parts with sizes as equal as possible. |
| 726 | LeetCode 726: Number of Atoms | Hard | Parse a chemical formula with nested parentheses, atom names, and multipliers using recursive descent. |
| 727 | LeetCode 727: Minimum Window Subsequence | Hard | Find the shortest substring of s1 that contains s2 as a subsequence using dynamic programming. |
| 728 | LeetCode 728: Self Dividing Numbers | Easy | Check each number in a range by extracting its digits and testing whether every digit divides the original number. |
| 729 | LeetCode 729: My Calendar I | Medium | Implement a calendar that accepts a booking only when it does not overlap with any existing booking. |
| 730 | LeetCode 730: Count Different Palindromic Subsequences | Hard | Count distinct non-empty palindromic subsequences using interval dynamic programming and duplicate handling. |
| 731 | LeetCode 731: My Calendar II | Medium | Allow double bookings but reject triple bookings using overlap interval tracking. |
| 732 | LeetCode 732: My Calendar III | Hard | Track the maximum number of overlapping calendar events using a sweep line difference map. |
| 733 | LeetCode 733: Flood Fill | Easy | Recolor the connected component containing the starting pixel using depth-first search. |
| 734 | LeetCode 734: Sentence Similarity | Easy | Check whether two word arrays are sentence-similar using a hash set of symmetric similar word pairs. |
| 735 | LeetCode 735: Asteroid Collision | Medium | Simulate asteroid collisions using a stack that keeps the surviving asteroids in order. |
| 736 | LeetCode 736: Parse Lisp Expression | Hard | Evaluate a Lisp-like expression with integers, variables, let bindings, addition, multiplication, and lexical scope. |
| 737 | LeetCode 737: Sentence Similarity II | Medium | Check sentence similarity with transitive word relationships using union-find. |
| 738 | LeetCode 738: Monotone Increasing Digits | Medium | Find the largest number less than or equal to n whose digits are monotone increasing using a greedy digit adjustment. |
| 739 | LeetCode 739: Daily Temperatures | Medium | Find how many days each temperature must wait for a warmer future day using a monotonic stack. |
| 740 | LeetCode 740: Delete and Earn | Medium | Transform the problem into House Robber dynamic programming by grouping equal values into total points. |
| 741 | LeetCode 741: Cherry Pickup | Hard | Maximize cherries collected on a round trip by converting the problem into two simultaneous forward paths and solving with dynamic programming. |
| 742 | LeetCode 742: Closest Leaf in a Binary Tree | Medium | Find the nearest leaf to a target node by converting the tree into an undirected graph and running breadth-first search. |
| 743 | LeetCode 743: Network Delay Time | Medium | Find the time needed for a signal to reach all nodes in a directed weighted graph using Dijkstra's algorithm. |
| 744 | LeetCode 744: Find Smallest Letter Greater Than Target | Easy | Use binary search to find the smallest character strictly greater than the target with wraparound handling. |
| 745 | LeetCode 745: Prefix and Suffix Search | Hard | Support fast prefix and suffix queries by indexing every prefix-suffix combination with the largest word index. |
| 746 | LeetCode 746: Min Cost Climbing Stairs | Easy | Find the minimum cost to reach the top of the staircase using dynamic programming. |
| 747 | LeetCode 747: Largest Number At Least Twice of Others | Easy | Find whether the maximum element is at least twice every other element using a single linear scan. |
| 748 | LeetCode 748: Shortest Completing Word | Easy | Find the shortest word that contains all required license plate letters using frequency counting. |
| 749 | LeetCode 749: Contain Virus | Hard | Simulate virus containment by repeatedly quarantining the most dangerous infected region and spreading the remaining regions. |
| 750 | LeetCode 750: Number Of Corner Rectangles | Medium | Count axis-aligned rectangles whose four corners are 1 using column-pair frequency counting. |
| 751 | LeetCode 751: IP to CIDR | Medium | A clear explanation of converting a range of IPv4 addresses into the shortest list of CIDR blocks using greedy bit manipulation. |
| 752 | LeetCode 752: Open the Lock | Medium | A clear explanation of solving Open the Lock using breadth-first search over lock states. |
| 753 | LeetCode 753: Cracking the Safe | Hard | A clear explanation of Cracking the Safe using a de Bruijn sequence and depth-first search over password states. |
| 754 | LeetCode 754: Reach a Number | Medium | A clear explanation of reaching a target on a number line using cumulative sums and parity. |
| 755 | LeetCode 755: Pour Water | Medium | A clear explanation of simulating water droplets over an elevation map by checking left first, then right. |
| 756 | LeetCode 756: Pyramid Transition Matrix | Medium | A clear explanation of solving Pyramid Transition Matrix using backtracking and memoization over pyramid rows. |
| 757 | LeetCode 757: Set Intersection Size At Least Two | Hard | A clear explanation of solving interval intersection constraints using greedy sorting and minimal point selection. |
| 758 | LeetCode 758: Bold Words in String | Easy | A clear explanation of marking matching substrings and merging overlapping bold ranges. |
| 759 | LeetCode 759: Employee Free Time | Hard | A clear explanation of finding common free time by merging all employee busy intervals and returning the gaps. |
| 760 | LeetCode 760: Find Anagram Mappings | Easy | A clear explanation of mapping each element in one array to a matching index in its anagram using a hash map. |
| 761 | LeetCode 761: Special Binary String | Hard | A clear explanation of making a special binary string lexicographically largest using recursive decomposition and sorting. |
| 762 | LeetCode 762: Prime Number of Set Bits in Binary Representation | Easy | A clear explanation of counting numbers whose binary representation has a prime number of set bits. |
| 763 | LeetCode 763: Partition Labels | Medium | A clear explanation of partitioning a string into the maximum number of parts so each character appears in at most one part. |
| 764 | LeetCode 764: Largest Plus Sign | Medium | A clear explanation of finding the largest plus sign in a mined grid using four directional dynamic programming scans. |
| 765 | LeetCode 765: Couples Holding Hands | Hard | A clear explanation of minimizing swaps so every couple sits together using greedy position tracking. |
| 766 | LeetCode 766: Toeplitz Matrix | Easy | A clear explanation of checking whether every top-left to bottom-right diagonal in a matrix has the same value. |
| 767 | LeetCode 767: Reorganize String | Medium | A clear explanation of rearranging characters so no two adjacent characters are equal using a greedy max heap. |
| 768 | LeetCode 768: Max Chunks To Make Sorted II | Hard | A clear explanation of splitting an array into the maximum number of chunks so sorting each chunk gives the fully sorted array. |
| 769 | LeetCode 769: Max Chunks To Make Sorted | Medium | A clear explanation of splitting a permutation into the maximum number of chunks using prefix maximums. |
| 770 | LeetCode 770: Basic Calculator IV | Hard | A clear explanation of simplifying algebraic expressions by parsing, substituting variables, and combining polynomial terms. |
| 771 | LeetCode 771: Jewels and Stones | Easy | A clear explanation of counting how many stones are jewels using a hash set for fast membership checks. |
| 772 | LeetCode 772: Basic Calculator III | Hard | A clear explanation of evaluating arithmetic expressions with parentheses, precedence, and integer division. |
| 773 | LeetCode 773: Sliding Puzzle | Hard | A clear explanation of solving the 2 x 3 sliding puzzle using breadth-first search over board states. |
| 774 | LeetCode 774: Minimize Max Distance to Gas Station | Hard | A clear explanation of minimizing the largest adjacent gas-station distance using binary search on the answer. |
| 775 | LeetCode 775: Global and Local Inversions | Medium | A clear explanation of checking whether every global inversion is also a local inversion using distance constraints. |
| 776 | LeetCode 776: Split BST | Medium | A clear explanation of splitting a binary search tree into two BSTs using recursion and pointer rewiring. |
| 777 | LeetCode 777: Swap Adjacent in LR String | Medium | A clear explanation of validating string transformation using two pointers and movement constraints. |
| 778 | LeetCode 778: Swim in Rising Water | Hard | A clear explanation of finding the minimum time to reach the bottom-right cell using a priority queue and minimax path reasoning. |
| 779 | LeetCode 779: K-th Symbol in Grammar | Medium | A clear explanation of finding the kth symbol in the grammar sequence using recursion and the parent-child relationship. |
| 780 | LeetCode 780: Reaching Points | Hard | A clear explanation of checking whether one point can reach another by working backward with modulo. |
| 781 | LeetCode 781: Rabbits in Forest | Medium | A clear explanation of finding the minimum possible number of rabbits using counting and greedy grouping. |
| 782 | LeetCode 782: Transform to Chessboard | Hard | A clear explanation of transforming a binary board into a chessboard using feasibility checks and minimum row and column swaps. |
| 783 | LeetCode 783: Minimum Distance Between BST Nodes | Easy | A clear explanation of finding the minimum difference between any two nodes in a BST using inorder traversal. |
| 784 | LeetCode 784: Letter Case Permutation | Medium | A clear explanation of generating all strings formed by independently changing each letter to lowercase or uppercase. |
| 785 | LeetCode 785: Is Graph Bipartite? | Medium | A clear explanation of checking whether an undirected graph can be split into two independent sets using graph coloring. |
| 786 | LeetCode 786: K-th Smallest Prime Fraction | Medium | A clear explanation of finding the kth smallest fraction from a sorted array using a min-heap. |
| 787 | LeetCode 787: Cheapest Flights Within K Stops | Medium | A clear explanation of finding the cheapest flight route with at most k stops using bounded Bellman-Ford relaxation. |
| 788 | LeetCode 788: Rotated Digits | Medium | A clear explanation of counting good numbers after rotating every digit by 180 degrees. |
| 789 | LeetCode 789: Escape The Ghosts | Medium | A clear explanation of deciding whether escape is possible by comparing Manhattan distances to the target. |
| 790 | LeetCode 790: Domino and Tromino Tiling | Medium | A clear explanation of counting tilings of a 2 x n board using dominoes and L-shaped trominoes with dynamic programming. |
| 791 | LeetCode 791: Custom Sort String | Medium | A clear explanation of rearranging a string so that selected characters follow a custom order. |
| 792 | LeetCode 792: Number of Matching Subsequences | Medium | A clear explanation of counting how many words are subsequences of a string using waiting queues. |
| 793 | LeetCode 793: Preimage Size of Factorial Zeroes Function | Hard | A clear explanation of finding how many integers have exactly k trailing zeroes in their factorial. |
| 794 | LeetCode 794: Valid Tic-Tac-Toe State | Medium | A clear explanation of validating whether a Tic-Tac-Toe board can occur in a legal game. |
| 795 | LeetCode 795: Number of Subarrays with Bounded Maximum | Medium | A clear explanation of counting contiguous subarrays whose maximum value lies inside a given inclusive range. |
| 796 | LeetCode 796: Rotate String | Easy | A clear explanation of checking whether one string can become another by repeated left rotations. |
| 797 | LeetCode 797: All Paths From Source to Target | Medium | A clear explanation of finding every path from node 0 to node n - 1 in a directed acyclic graph using DFS and backtracking. |
| 798 | LeetCode 798: Smallest Rotation with Highest Score | Hard | A clear explanation of finding the smallest rotation with maximum score using a difference array. |
| 799 | LeetCode 799: Champagne Tower | Medium | A clear explanation of simulating overflow in a champagne glass pyramid using dynamic programming. |