LRDI Questions for CAT: Solve Network Puzzles Fast
Among LRDI questions for CAT, few punish guesswork as visibly as a network set: six cities connected by flights, some direct, some not, and a request for the cheapest route between two of them under a handful of conditions. Twenty minutes in, an aspirant has drawn the same diagram three times, crossed out two of them, and still is not confident the third one is even correct.
Network and route puzzles punish a specific habit: solving by trial instead of by structure. The diagram is not the hard part. Deciding what to diagram, and in what order to apply the given conditions, is what actually separates a set solved in eight minutes from one abandoned at the eighteen minute mark.
Want a real sense of how these sets are currently costing you time? Go practice CAT Network Flow Diagram questions and time yourself set by set, not just question by question.
- Network and route puzzles in CAT DILR reward a fixed diagramming order more than raw logical speed.
- The Shortest Path Method gives you four steps: map the nodes, list the constraints as edges, eliminate impossible routes first, then verify the survivor.
- Redrawing the same diagram from scratch after each new condition is the single biggest time sink in these sets.
- A simple adjacency table often resolves a route question faster than a full visual network diagram.
- This is a chapter that rewards deliberate, repeated practice more than most, because the diagramming habit only forms through repetition.
Why Network and Route Puzzles Eat So Much Time
Most CAT DILR sets reward careful reading. Network and route sets add a second demand on top of that: an external representation, a diagram or table, that has to be built correctly before you can reason about it at all. Get the representation wrong, and every conclusion drawn from it is wrong too, no matter how sound your logic is on top of it.
The instinct under time pressure is to start diagramming immediately, before all the conditions have been read. That produces exactly the redraw cycle described above, because a diagram built on partial information almost always needs to be scrapped once the remaining conditions arrive.
Watching the clock makes this worse, not better. The more aware you are of time slipping away, the stronger the pull to start marking something down immediately rather than spending another thirty seconds reading. That thirty seconds is almost always the cheaper trade, and treating it as time well spent rather than time lost is the mindset shift this method depends on.
Mentors reviewing DILR scripts notice that the aspirants who solve network sets fastest are rarely the ones who draw the most polished diagram. They are the ones who read every condition once, in full, before committing pen to paper at all.
The Shortest Path Method
Run these four steps in order, every time. The method does not change based on how many nodes or conditions a set has, which is exactly what makes it fast to apply under pressure.
Step 1: Map the Nodes First, Nothing Else
Before touching a single connection, list every node the set mentions, cities, people, tasks, whatever the set's entities are. Do this from a full read of the set, not question by question. A missed node discovered halfway through is what forces a full redraw.
Step 2: List Every Constraint as an Edge, Not a Sentence
Convert each condition into a direct connection or a ruled out connection between two nodes, rather than keeping it as a sentence you have to reread. "A is directly reachable from B" becomes a single marked edge. "A is never directly reachable from C" becomes a marked absence. This conversion is what makes Step 3 possible.
Step 3: Eliminate Impossible Routes Before Building Good Ones
Rather than trying to construct the shortest route directly, first rule out every route that violates a marked absence from Step 2. What survives is usually a small enough set of candidates that the actual shortest or cheapest route is easy to spot by inspection.
Step 4: Verify the Survivor Against Every Condition, Once
Before submitting an answer, check the surviving route against every original condition a single time, in order. This catches the one common error the method otherwise misses, a route that satisfies most conditions but happens to violate one stated late in the set.
Diagram or Table: Choosing the Right Representation
Not every network set needs a full visual diagram. When the number of nodes is small and the question only asks about a specific pair, a simple adjacency table, nodes down the side, nodes across the top, a mark in each cell showing connected or not, resolves the question faster than drawing a full network by hand.
| Set characteristic | Better representation | Why |
|---|---|---|
| Fewer than 6 nodes, simple yes or no connections | Adjacency table | Faster to build and scan than a drawn diagram |
| 6 or more nodes, weighted routes or costs | Visual network diagram | Costs and multi step paths are easier to trace visually |
| Question asks for a single specific route | Adjacency table, focused on relevant nodes only | No need to map the entire network to answer one pair |
| Question asks for a global property, most connected node, total routes | Full diagram | Global properties need the whole structure visible at once |
Before you start drawing anything, glance at all the questions in the set, not just the first one. If every question only asks about one or two specific nodes, an adjacency table focused on those nodes will answer the whole set faster than a full network diagram ever would.
How Network Sets Differ From Other CAT DILR Questions
It helps to be clear about what makes network and route sets genuinely different from the arrangement and grouping sets that make up most of CAT DILR, rather than treating the whole section as one undifferentiated skill.
Arrangement sets, seating people around a table or scheduling events into slots, mostly reward tracking a fixed set of positions against a list of constraints. Network sets add a layer arrangement sets do not have: the connections themselves are the object being reasoned about, not just the positions of the entities. That is exactly why a representation built for arrangement sets, a simple grid of who sits where, does not transfer cleanly to a network set, and why treating every DILR set with the same generic diagramming habit under performs a method built specifically for connections.
A Worked Example: Six Cities, One Cheapest Route
Take a set with six cities and a handful of direct flight costs given, plus two conditions ruling out certain direct connections. Step 1 lists all six cities before anything else. Step 2 converts every given flight cost and every ruled out connection into marked edges and marked absences on a table. Step 3 eliminates any route that uses a ruled out connection, which in a typical set removes most of the seemingly obvious candidates immediately.
What usually survives is one or two candidate routes, at which point simple addition settles the cheapest one. Step 4 checks that survivor against the two ruling out conditions one final time, catching the specific trap CAT often builds in: a cheap route that happens to use a connection ruled out by a condition stated in the set's final sentence, easy to miss if you stopped rereading conditions after Step 2.
Notice how little of this example depended on the number six specifically. The same four steps apply whether a set has four cities or nine, because the method scales with the number of conditions you convert into edges, not with the raw size of the network. A set that feels intimidating because it lists eight or nine cities is often no harder than a four city set once the conditions are properly converted, and recognising that early keeps the size of a set from triggering unnecessary panic before you have even started reading it properly.
- Read the entire set once before drawing anything.
- List every node mentioned, even ones that seem irrelevant to the first question.
- Convert every condition into a marked edge or a marked absence.
- Eliminate routes that violate a marked absence before evaluating cost or length.
- Verify the surviving route against every condition once more before answering.
Where This Method Breaks Down
Two recurring mistakes undo the method even when the diagramming itself is correct.
Starting to Diagram Before Reading Every Condition
This is the single biggest cause of the redraw cycle. A diagram built after only half the conditions are read will almost certainly need rework once the rest arrive, costing more time than the extra thirty seconds of full reading would have.
Skipping the Final Verification Step
Under time pressure, Step 4 is the easiest step to drop. It is also the step that catches the specific trap conditions CAT tends to place late in a set's description, so dropping it trades a small time saving for a real risk of a wrong answer. Budget the verification step into your time estimate for the set from the start, rather than treating it as an optional extra you only get to if time allows, since it consistently pays for itself across a full mock.
- Do you read the entire set once before drawing any part of the diagram?
- Do you convert conditions into marked edges and absences rather than rereading sentences repeatedly?
- Do you choose a table over a full diagram when the question only concerns one or two nodes?
- Do you verify your final answer against every condition once more before submitting?
This method only becomes fast with repetition on real sets. Go practice Network Flow Diagram questions for CAT preparation and apply the four steps deliberately on every set, timing how much of your total time each step actually takes.
Network and route puzzles are one part of a broader DILR skill set. Our CAT DILR practice question bank covers all 15 chapters, so you can see how this same structured, step first approach transfers to arrangement and selection sets too.
For a sense of how network puzzles have actually appeared on real papers, our CAT exam previous year DILR questions with solutions show the exact style and difficulty CAT has used in recent years. If you are still deciding how much weight to give DILR relative to Quant and VARC in your overall plan, our CAT preparation strategy review is a useful gut check before you commit the next month's schedule.
Build a Focused DILR Practice Plan
Optima Learn's topic priority system flags exactly which DILR set types are costing you the most time, so your practice hours go toward network and route puzzles specifically instead of a random mix across every set type.
Build My DILR Practice PlanFrequently Asked Questions About LRDI Questions for CAT
How common are network and route sets in CAT DILR?
They appear regularly across CAT DILR slots, often as one of the sets built around cities, flights, or connections, making them common enough to prepare for specifically rather than treating each one as a fresh puzzle type.
Should I always draw a full network diagram for these sets?
No. When a set has few nodes or the questions only concern one or two specific connections, an adjacency table is usually faster to build and just as reliable to read.
What is the biggest time sink in network and route puzzles?
Redrawing the diagram after realising a condition was missed on the first pass. Reading every condition fully before drawing anything is the single highest leverage habit change available here.
How do I practice network and route puzzles effectively?
Apply the same four step method every time, on real sets, and track how long each step actually takes you. The method becomes fast only once it stops requiring conscious effort to follow, which takes deliberate repetition.
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