LeetCode

Coding Interview

Jason Yang · 31 Mar, 2026

Minimum Window Substring (LeetCode 76): the sliding-window O(n) approach with character counts to shrink to the smallest valid window, with a visual.

Coding Interview

Jason Yang · 31 Mar, 2026

Longest Substring Without Repeating Characters (LeetCode 3): the sliding-window O(n) approach, and why the int[128] version can jump the left pointer instead of stepping — with interactive visuals.

Coding Interview

Jason Yang · 31 Mar, 2026

Valid Palindrome (LeetCode 125): the two-pointer O(n) check that skips non-alphanumerics in place, why it beats building a cleaned string, and the edge cases.

Coding Interview

Jason Yang · 30 Mar, 2026

Longest Consecutive Sequence (LeetCode 128): the hash-set O(n) trick that only counts from sequence starts, with an interactive step-by-step visual.

Coding Interview

Jason Yang · 27 Mar, 2026

3Sum (LeetCode 15): sort then two-pointer for an O(n^2) solution, why sorting unlocks it, and the three places duplicate triplets sneak in — with an interactive visualization.

Coding Interview

Jason Yang · 27 Mar, 2026

Container With Most Water (LeetCode 11): the two-pointer O(n) approach, and the short proof for why moving the shorter line never skips a better answer — with an interactive visualization.

Coding Interview

Jason Yang · 03 Dec, 2025

Search in Rotated Sorted Array (LeetCode 33): a modified O(log n) binary search that finds which half is sorted, with an interactive step visual.

Coding Interview

Jason Yang · 02 Dec, 2025

Find Minimum in Rotated Sorted Array (LeetCode 153): the O(log n) binary search that locates the rotation pivot, explained step by step with examples.

Coding Interview

Jason Yang · 01 Dec, 2025

Maximum Product Subarray (LeetCode 152): why you track max and min together to handle negatives and zeros, and the O(n) dynamic-programming solution.

Coding Interview

Jason Yang · 29 Nov, 2025

Maximum Subarray (LeetCode 53): Kadane's algorithm explained as one decision — extend or restart — plus the O(n) to O(1) space drop and a full worked trace.

Coding Interview

Jason Yang · 28 Nov, 2025

Product of Array Except Self (LeetCode 238): the prefix and suffix product trick that avoids division for an O(n) solution, with an interactive visual.

Coding Interview

Jason Yang · 27 Nov, 2025

Contains Duplicate (LeetCode 217): compare the brute-force, sorting, and hash-set approaches — and why 'just use a hash set' isn't always the right reflex.

Coding Interview

Jason Yang · 26 Nov, 2025

Best Time to Buy and Sell Stock (LeetCode 121): the single-pass O(n) solution that tracks the lowest price so far, with an interactive step-by-step visual.

Coding Interview

Jason Yang · 11 Nov, 2025

Two Sum (LeetCode 1) two ways: the brute-force O(n^2) scan vs the hash-map O(n) approach — with the intuition, edge cases, and the space-time trade-off.