6 articles
LeetCode 565 — asked at Amazon and Google. Find the longest cycle in a functional graph where each index maps to nums[index]. Mark visited nodes in-place (set to n) to avoid revisiting. O(n) time, O(1) extra space — classic cycle detection pattern.
A directed graph cycle-detection problem solved by Kahn topological sort (BFS) or three-color DFS. The bedrock template behind dependency resolution at Maven, npm, Bazel, Make, and every modern build system.
Find the edge that closes a cycle when added to an n-node, n-edge graph. The first edge whose two endpoints share a Union Find root is the answer — a five-line solve.
LC 141 Linked List Cycle is a classic interview question asked by Amazon, Microsoft, and Google that tests your mastery of the two-pointer fast/slow technique. Learn Floyd's tortoise and hare algorithm with a visual dry run, Python and JavaScript solutions, and key interview tips.
LC 142 Linked List Cycle II is a medium interview problem at Amazon, Microsoft, and Google where you find the exact node where a cycle begins using Floyd's algorithm and a mathematical proof. Learn the two-phase approach with Python and JavaScript, the math proof, visual dry run, and common interview questions.
LC 287 Find the Duplicate Number is a brilliant medium interview problem at Amazon, Google, and Facebook where you find a duplicate in an n+1 integer array in O(1) space by treating the array as an implicit linked list and applying Floyd's cycle detection algorithm. Master the connection between arrays and linked lists with Python and JavaScript solutions and detailed proof.