CustomCC0-1.0#cptp0172200
Range LCM Updates
Summary
- •Phase 5 / segment_tree, lazy_propagation
- •Reasoning-first competitive programming drill
Problem Description
Given an array of n integers, perform q operations of two types: (1) Update all elements in range [l, r] to their LCM with x, (2) Query the GCD of all elements in range [l, r].
How to read this problem in plain language:
- This is a Phase 5 reasoning drill focused on segmen, laz.
- Typical lenses to test first: segment-tree, gcd, lcm.
- Constraints reminder: 1 ≤ n,, 1 ≤ ai,
Mini examples for mental simulation:
1) Boundary example: Describe why this case is tricky. Explain expected behavior and why naive logic may fail.
2) Adversarial example: Adversarial case where naive greedy/local decision looks correct but fails globally.
Lite-mode writing target:
- Write 1~2 observations that shrink the search space.
- Name one final algorithm and state target complexity explicitly.
- Validate with at least 2 edge cases and one hand simulation.
Constraints
- •1 ≤ n,, 1 ≤ ai,
Analysis
Key Insight
The goal is to force explicit intermediate reasoning before revealing more.
segment-treegcdlcmrange-updates