Interval-dp

2 articles

dsa10 min read

Burst Balloons — Interval DP with Reverse Thinking (The Hardest Grid DP Pattern)

LC 312 Burst Balloons is the classic hard-level interval DP problem asked at Google, Amazon, and Meta. The key insight is thinking in reverse — instead of choosing which balloon to burst first, choose which one to burst last in each interval. This transforms an impossible ordering problem into clean O(n^3) DP.

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dsa8 min read

Strange Printer — Interval DP with Merge-on-Match

LeetCode 664 Strange Printer is the canonical O(n^3) interval DP every senior FAANG interviewer expects you to handle. We derive the dp[i][j] recurrence, walk through the merge-on-match optimization, dry-run a full table, and discuss where Strange Printer sits in the Burst Balloons / MCM family.

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