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Zonal Informatics Olympiad
IARCS Stage-1 informatics olympiad. Pen-and-paper paper on algorithmic problem-solving — no programming language knowledge required. 4 problems in 3 hours.
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Measuring Algorithm EfficiencyA nested loop structure has the outer loop running n times and the inner loop running m times. What is the time complexity?
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ZIO — Quick Practice
FULL20 questions · 180 min
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What can I get from ZIO?
Mock-score → expected rank → likely outcome. Use the mocks below to find your current band, then plan how many marks you need to climb.
IOI track — Elite tier
92–100% · Post-based exam (no numeric rank)
National-level excellence
82–92% · Post-based exam (no numeric rank)
Top zonal performers
70–82% · Post-based exam (no numeric rank)
INOI qualification likely
55–70% · Post-based exam (no numeric rank)
Borderline qualification zone
35–55% · Post-based exam (no numeric rank)
Below qualifying threshold
0–35% · Post-based exam (no numeric rank)
AI-curated from historic cut-off patterns. Always verify with the latest official notification before making decisions.
IARCS has confirmed that details for ICO-2027 (including ZIO-2027) will be announced in the second half of September 2026, with registrations opening in October 2026.
The International Olympiad in Informatics 2026 will take place in Tashkent, Uzbekistan from August 9–16, 2026. 36 Indian students qualified for IOITC-2026 to compete for team selection.
Swasti Vitthal Patil won India's first-ever gold medal at EGOI-2026 in Italy. Mansi Sane won silver and Diya Sathishdev won bronze, showcasing the strength of India's Informatics Olympiad pathway.
767 students registered for ZIO-2026, with 612 appearing for the exam held on 15 November 2025. 152 students qualified through ZIO for the Indian National Olympiad in Informatics.
🏅IOI-2026 (International Olympiad in Informatics) in Tashkent
30 days awaySun, 9 Aug, 2026
August 9–16, 2026; India's top 4 students from IOITC compete
ICO-2027 details announcement expected
75 days awayWed, 23 Sept, 2026
Second half of September 2026 per IARCS
ICO-2027 registration opens
95 days awayTue, 13 Oct, 2026
Expected October 2026; fee typically Rs 472 (Rs 400 + GST)
ICO-2027 registration deadline (expected)
115 days awayMon, 2 Nov, 2026
Typically end of October/early November
🏅ZIO-2027 exam date (expected)
130 days awayTue, 17 Nov, 2026
Typically mid-November; 3-hour written exam at 35+ centres
ZIO-2027 results expected
160 days awayThu, 17 Dec, 2026
Typically announced in December
Click any topic to read study notes
Introduction to Algorithms
What an algorithm is, step-wise problem decomposition, pseudocode reading.
Measuring Algorithm Efficiency
Time and space complexity intuition, big-picture growth rates without formal Big-O.
Searching
Linear search, binary search and variants over sorted/unsorted data.
Sorting
Selection, insertion, merge and quick sort intuition; stability and order properties.
Recursion
Recursive thinking, base/recursive cases, recursion tree, divide-and-conquer.
Dynamic Programming Intuition
Overlapping subproblems, memoisation, tabulation on small input sizes.
Greedy Algorithms
Local optimal choices, interval scheduling, coin-change-style ad-hoc greedy.
Basic Graph Concepts
Vertices, edges, directed/undirected graphs, paths, cycles, connectivity.
Graph Traversal
Breadth-first and depth-first traversal as conceptual exploration strategies.
Shortest Paths
Shortest-path intuition on grids and small graphs without formal algorithms.
Trees
Rooted trees, binary trees, parent/child traversal, tree counting puzzles.
Basic Data Structures
Arrays, lists, stacks, queues — used as tools for problem modelling.
Simulation
Mentally or on paper simulating a process or rule on small concrete inputs.
Invariants and Monovariants
Quantities preserved or strictly changing across steps — proving outcomes.
Case Analysis
Splitting a problem into exhaustive cases and resolving each.
Counting Principles
Sum and product rules, permutations, combinations applied to small enumerations.
Pigeonhole Principle
Existence arguments via pigeons/holes — colourings, residues, pairs.
Parity and Modular Reasoning
Even/odd reasoning, basic modular arithmetic for invariants.
Elementary Number Theory
Divisibility, gcd/lcm reasoning, prime factorisation puzzles.
Combinatorial Games
Winning/losing positions, Nim-like games, strategy stealing.
Constructive Problems
Building an explicit example/configuration that satisfies given rules.
Optimisation Puzzles
Finding minimum/maximum of a quantity under given constraints.
Scheduling and Ordering
Sequencing tasks, jobs or moves to satisfy precedence/deadline rules.
Grid and Geometry Puzzles
Reasoning on 2D grids — paths, colourings, tilings, distance puzzles.
Three Concrete Inputs Format
ZIO-style problems — solve three increasingly large concrete inputs by spotting an efficient method.
🏅INOI-2027 exam date (expected)
220 days awayMon, 15 Feb, 2027
Typically mid-February; programming exam in C++
Sets and Logic
Inclusion-exclusion, propositional logic, truth tables in puzzles.