Linked List Cycle II in Java (Find Cycle Start)
This is one of the best fast-and-slow pointer problems because it has two phases: first prove a cycle exists, then find the exact node where the cycle begins.
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First Missing Positive in Java
This is one of the most famous index-placement problems. The hard part is not the swap itself, but recognizing that the answer must lie in the range 1..n+1 f...
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This problem looks like ordinary binary search, but one match is not enough. We need the full boundary of the target block, so we intentionally bias one sear...
Find Minimum in Rotated Sorted Array in Java
This is one of the most useful “binary search on structure” problems. We are not searching for a target value. We are searching for the boundary where sorted...
Remove Linked List Elements in Java
This is a basic but important linked-list deletion pattern. The key lesson is that deleting by value is really about rewiring pointers safely, especially whe...