JZLeetCode
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Featured
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LeetCode 395 Longest Substring with At Least K Repeating Characters
Solutions for LeetCode 395, medium, tags: hash table, string, divide and conquer, sliding window.
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LeetCode 241 Different Ways to Add Parentheses
Solutions for LeetCode 241, medium, tags: math, dynamic programming, string, recursion, memoization.
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LeetCode 1448 Count Good Nodes in Binary Tree
Solutions for LeetCode 1448, medium, tags: tree, depth-first search, breadth-first search, binary tree.
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LeetCode 503 Next Greater Element II
Solutions for LeetCode 503, medium, tags: array, stack, monotonic stack.
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LeetCode 542 01 Matrix
Solutions for LeetCode 542, medium, tags: array, dynamic programming, bfs, matrix.
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LeetCode 377 Combination Sum IV
Solutions for LeetCode 377, medium, tags: array, dynamic programming.
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LeetCode 2439 Minimize Maximum of Array
Solutions for LeetCode 2439, medium, tags: array, binary search, greedy, prefix sum.
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LeetCode 226 Invert Binary Tree
Solutions for LeetCode 226, easy, tags: tree, depth-first search, breadth-first search, binary tree.
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LeetCode 451 Sort Characters By Frequency
Solutions for LeetCode 451, medium, tags: hash table, string, sorting, heap, bucket sort.
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LeetCode 2130 Maximum Twin Sum of a Linked List
Solutions for LeetCode 2130, medium, tags: linked list, two pointers, stack.
Recent Posts
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System Design - How Debuggers Work
How debuggers like GDB and LLDB work under the hood: ptrace system call, INT3 software breakpoints, hardware watchpoints, single-stepping, DWARF debug info, and source code walkthrough from the GDB and Linux kernel.
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System Design - How SQLite Works Internally
How SQLite works internally: the tokenizer, parser, bytecode compiler, virtual machine (VDBE), B-tree storage engine, pager, and WAL — a complete walkthrough of how a SQL statement travels from text to disk in the world's most deployed database.
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System Design - How Linux Signals Work
How Linux signals work: signal delivery from kernel to userspace, signal dispositions, the sigaction machinery, signal masks, real-time vs standard signals, and a source code walkthrough of the Linux kernel signal path.
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System Design - How Diff Algorithms Work
How diff algorithms work: the edit graph model, shortest edit script, Myers' O(ND) algorithm with greedy snakes and D-contours, git's diff strategies (Myers, patience, histogram), and a source code walkthrough of xdiff in the git codebase.
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System Design - How Floating Point Arithmetic Works (IEEE 754)
How IEEE 754 floating point works: the sign-exponent-mantissa bit layout, normalization, special values (infinity, NaN, denormals), rounding modes, and why 0.1 + 0.2 != 0.3 — with binary walkthroughs and real source code.
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System Design - How Hardware Interrupts and Trap Handling Work
How hardware interrupts work: the interrupt lifecycle from electrical signal to handler execution, IDT, IRQs, top-half/bottom-half processing, and a Linux kernel source code walkthrough.
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LeetCode 442 Find All Duplicates in an Array
Solutions for LeetCode 442, medium, tags: array, hash table.
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LeetCode 930 Binary Subarrays With Sum
Solutions for LeetCode 930, medium, tags: array, hash table, sliding window, prefix sum.