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The complete 2D Dynamic Programming roadmap for FAANG interviews — LCS, Edit Distance, grid path counting, interval DP, stock state machines, and 2D knapsack with Python and JavaScript templates.
LC 62 Unique Paths is the foundational 2D grid DP problem at Amazon, Google, and Meta. Learn the recurrence, space-optimize to 1D, and master the combinatorics shortcut interviewers love to ask about.
LC 63 Unique Paths II extends the classic grid DP with obstacle cells. Master the obstacle-zeroing pattern, handle blocked start/end edge cases, and space-optimize to O(n) — the exact follow-up interviewers throw immediately after Unique Paths.
LC 64 Minimum Path Sum is the essential cost-minimization variant of grid DP, asked heavily at Amazon and Google. Learn the 2D recurrence, space-optimize to O(n), and understand why bottom-up tabulation handles borders without special-casing.
LC 120 Triangle asks for the minimum-sum path from apex to base. The bottom-up DP approach eliminates border initialization complexity and achieves O(n) space — a classic 2D DP problem that tests your ability to work on non-rectangular structures.