What is AtCoder Beginner Contest 452?

ABC452 is a rated contest for beginners, problems A-D scaling from simple conditionals to string DP-ish. Held recently, Python-friendly.

How to solve ABC452 Problem D?

Use two pointers on right endpoint per left start, with greedy subsequence check for T in substring. Count pre-first-match endings.

Why did ABC452 Problem C need sets?

Precompute possible chars per position from M strings; check candidates against sets in O(N) per.

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AtCoder ABC452 Dissected: Python Wins, But D's Trap Nearly Bites

AtCoder Beginner Contest 452 hit with deceptively simple A-B starters, then cranked up the heat in C and D. One contestant's near-TLE in D reveals timeless algo lessons.

Open Source Beat Apr 11, 2026 4 min read

AtCoder Beginner Contest 452 problems A-D with Python code snippets

⚡ Key Takeaways

ABC452 A-B are geometry/conditionals disguised as easy points. 𝕏
C's set precomp handles M=2e5 elegantly — O(MN) flies. 𝕏
D's window + greedy check works but risks O(n^2); profile for safety. 𝕏

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Originally reported by Dev.to

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