The third round of the 2026 USACO season has officially concluded. At the same time, results for the second contest—previously delayed due to academic integrity reviews—have now been fully released.
In the second contest of the 2026 USACO season, students from Shenzhen Foreign Languages School International Division, Affiliated High School of South China Normal University International Division, BASIS Guangzhou, Soong Mei-ling School, Chengdu Tianli School, and Westover School achieved strong results. One student advanced to Platinum, three to Gold, and eleven to Silver. Additionally, two Bronze-level students achieved perfect scores and were promoted to Silver. More results are still being updated.
For Round 3, instructors Jiang and Wei from Hanlin Computer Science provided in-depth breakdowns of the Bronze, Silver, and Gold divisions, covering key concepts and detailed walkthroughs of the official problems. Let’s dive into the analysis.
Immediately following each competition, Hanlin mentors provide a prompt analysis of the exam, producing a comprehensive package of [Video Explanations + Suggested Answers] for every set of questions. This resource is designed to help you prepare more effectively for future competitions. Students and parents interested in obtaining these materials can scan the QR code to claim them for free!
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Bronze Division Analysis
Score Trends
The official cutoff for Round 3 has not yet been announced. Based on historical data and this contest’s difficulty, the cutoff is expected to be around 700–750.
Difficulty Overview
This Bronze round was slightly easier than the first two contests of the season. Problems 1 and 3 followed relatively standard approaches, while Problem 2 required deeper observation and pattern recognition. Notably, recent Bronze problems have increasingly involved binary-related thinking. Given past cutoff trends, most participants should find it manageable to reach promotion scores.
Key Problem Insights
Problem 1: Greedy + Sorting
This problem involves modular arithmetic. By grouping numbers based on their remainder modulo K, we observe that only numbers with the same remainder can potentially become equal after adding K repeatedly. Within each group, we sort the quotients and apply a greedy strategy to ensure they form a strictly increasing sequence with minimal operations. Whenever a conflict occurs, incrementing by exactly one step ensures optimality.
Problem 2: Ad Hoc Pattern Discovery
This problem asks for the minimum number of operations to reduce a large number x to zero under specific rules. Direct simulation is infeasible due to the size constraint (up to 10^(2×10^5)). The key insight is transforming the number into a binary-like structure. From there, the total number of operations can be simplified to a formula:
total operations = val + floor(val / 2).
This reduces a complex iterative process into a straightforward mathematical computation. The challenge lies in recognizing the pattern through small-scale simulations.
Problem 3: Greedy + Simulation
This is a string transformation problem involving two types of swaps: within a string and between two strings. The solution processes the string from left to right, always choosing the lowest-cost operation first. Each position can be fixed in at most two operations, making the greedy approach both efficient and optimal.
Summary
The Bronze division tested a mix of mathematical reasoning, greedy strategies, and simulation skills. Problem 2 especially highlights the importance of discovering hidden patterns rather than relying on standard templates.
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Silver Division Analysis
Score Trends
The expected cutoff remains around 700–750 based on previous contests.
Difficulty Overview
The difficulty level is similar to the second contest. While fewer classic algorithms were required, the problems demanded strong logical reasoning and flexible use of data structures. Achieving full scores was slightly harder than in the previous round.
Key Problem Insights
Problem 1: Greedy + Simulation + Data Structures
This problem combines multiple techniques, including priority queues, queues, prefix sums, and binary search. The main challenge is avoiding timeouts by identifying cycles in the simulation. Once a repeating pattern is detected, the simulation can be optimized into two phases: entering the cycle and processing within the cycle. Prefix sums and binary search are then used to compute results efficiently.
Problem 2: Math + Segment Tree
This problem revolves around modeling water flow across buckets with periodic flipping behavior. By deriving recurrence relations for each bucket’s flipping time and start time, we can compute the total water flow mathematically. Due to dynamic updates, a segment tree is required for efficient recalculation. While full implementation is complex, partial solutions can still earn significant points.
Problem 3: Greedy + Parity Constraints
This problem focuses on constructing valid pairings under parity constraints. By segmenting values and analyzing odd-even properties, we determine feasible matching ranges. The final step involves combining results from two dimensions and verifying both range coverage and parity consistency.
Summary
Silver problems continue to emphasize pattern recognition, greedy construction, and logical reasoning rather than heavy algorithmic implementation. Future preparation should focus on these areas alongside core algorithms.
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Gold Division Analysis
Score Trends
The expected cutoff is likely around 700–750.
Difficulty Overview
This round was notably challenging, emphasizing mathematically driven algorithm design. Problems 2 and 3, in particular, required deep logical reasoning and abstraction.
Key Problem Insights
Problem 1: BIT + Greedy + Rotation
This problem involves analyzing a permutation under cyclic shifts. A Binary Indexed Tree (Fenwick Tree) is used to efficiently compute inversion-related metrics. The key idea is converting dynamic rotation effects into static contribution changes using difference arrays, then finding the optimal shift via a greedy scan.
Problem 2: Shortest Path + Logical Inference
A highly complex graph problem involving reachability constraints and logical validation. The solution builds distance structures using BFS or Dijkstra and applies reverse reasoning to determine valid states. This problem requires precise control over graph traversal and condition handling.
Problem 3: Tree Combinatorics + Modular Arithmetic
This problem combines tree structures with combinatorics. By precomputing factorials and modular inverses, and analyzing subtree sizes, the solution derives a counting formula for valid configurations. This type of problem demands strong mathematical intuition and familiarity with tree-based dynamic programming.
Summary
The Gold division tested a broad range of advanced skills:
- Problem 1 focused on data structure optimization.
- Problem 2 emphasized complex graph modeling and logical reasoning.
- Problem 3 required deep understanding of combinatorics and tree algorithms.
Overall, the contest highlights a shift toward evaluating mathematical abstraction and problem modeling rather than just implementation skills.
Content and Video Explanations by Hanlin Computer Science Instructors
The above analysis and video explanations were prepared by Instructor Wei and Instructor Jiang from Hanlin Computer Science.
Instructor Wei
Hanlin Computer Science Instructor
- Master’s Degree in Software Engineering, Tsinghua University
- Bachelor’s Degree in Software Engineering, Nanjing University
Instructor Wei is known for being patient and highly responsible with students. His teaching style simplifies complex concepts and adapts to individual learning needs. He communicates actively with students, adjusts teaching pace in real time, and focuses on key learning priorities to maximize outcomes within limited time.
Teaching Achievements (Selected)
- One-on-one student advancement rates:
- Silver: 85%
- Gold: 60%
- Platinum: 25%
- Coached a 7th-grade student to advance to USACO Gold
- Guided a student to join the New Zealand national team within one year
Recent Results:
- 2024–2025 USACO Season:
- 16 students advanced to Silver
- 14 students advanced to Gold
- 2 students advanced to Platinum
- 2023–2024 USACO Season:
- 14 students advanced to Silver
- 9 students advanced to Gold
- 1 student advanced to Platinum
- 2022–2023 USACO Season:
- 11 students advanced to Silver
- 5 students advanced to Gold
Instructor Jiang
Hanlin Computer Science Instructor
- East China Normal University
- Combined Bachelor’s and Master’s Program in Computer Science (Top 4 direct admission)
Instructor Jiang integrates ACM and USACO problems with industry-level coding standards. His teaching includes:
- A dynamic difficulty adaptation system that identifies student weaknesses in real time and adjusts training plans accordingly
- A structured approach to algorithmic thinking
- Competition psychology training tailored for IOI and USACO formats
Teaching Achievements (Selected)
- 2024 Season Results:
- 3 students advanced to Gold (including 2 middle school students)
- 5 Gold-level students all successfully advanced further
- Developed a unique “Algorithm Thinking Decomposition Method”
- Helped students progress from Bronze to Gold within 3 months
- Fastest improvement achieved in just 8 weeks
Struggling with USACO Preparation? Hanlin Can Help
Hanlin has many years of experience in USACO competition training.
The curriculum is independently developed and continuously updated by the Hanlin academic team. It supports C++, Python, and Java, and covers past USACO problems categorized by topic. Each concept is paired with example problems and exercises, with explanations that progress from basic to advanced levels.
Past contest problems are also organized into five difficulty tiers, enabling students to systematically improve their problem-solving skills step by step.
USACO Course Offerings
In addition to one-on-one coaching, Hanlin offers a variety of small-group classes:
Pre-USACO Foundation Course
- Class size: 3–8 students
- Total hours: 30
- Start date: March 7
USACO Bronze Full Course
- Class size: 3–8 students
- Total hours: 40
- Start date: March 2
USACO Silver Full Course
- Class size: 3–8 students
- Total hours: 50
- Start date: March 7
USACO Gold Full Course
- Class size: 3–8 students
- Total hours: 60
- Start date: March 7
Enroll in Hanlin’s official USACO courses to receive the full set of course materials for free.
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