Reverse Nodes in K-Group (incomplete tail variant)

Examples Example 1 Example 2 Requirements You receive a linked-list head and an integer k. Reverse nodes in consecutive blocks of k, then return the resulting list head. Known interview variations include: Also reverse an incomplete last block (a nonstandard variation) — unlike the usual LeetCode behavior, which preserves a remaining block smaller than k, some interview prompts require that leftover block to be reversed as well. A two-stage warmup: begin by coding an…