Numbers With Same Consecutive Differences
A medium-tier problem at 59% community acceptance, tagged with Backtracking, Breadth-First Search. Reported in interviews at Flipkart and 0 others.
You hit this problem on a Flipkart OA and you're blank. Build all numbers of length N where each digit differs from the next by exactly K. Sounds constrained, but most candidates freeze on the state representation. Is it DFS or BFS? Do you prune early or explore everything? You've got valid intuitions about backtracking but the implementation can spiral. If you blank on the exact pattern during the live assessment, StealthCoder surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "Numbers With Same Consecutive Differences"
Numbers With Same Consecutive Differences is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Made by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE.
Get StealthCoderThe trick is recognizing that you're not searching a traditional graph, you're building strings digit-by-digit with a hard constraint. Start with each digit 1 to 9 as the root of a tree. From each current digit, you can only move to current plus K or current minus K, but they must stay in 0-9 range. Backtracking works cleanly here: build a path of length N by recursively appending valid next digits, then backtrack and try the next option. Most candidates either forget to check bounds on the next digit or try to brute-force all N-digit numbers first and filter. Both kill performance. The clean version uses DFS with early termination. BFS also works but wastes space on a queue when recursive backtracking is more natural. If this problem hits your live OA and you blank on the digit-by-digit recursion structure, StealthCoder runs invisibly and solves it.
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Numbers With Same Consecutive Differences recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Made by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Numbers With Same Consecutive Differences interview FAQ
Is this really a medium problem or does the acceptance rate lie?+
Acceptance sits around 59%, which tracks medium difficulty. The conceptual leap is not huge, but the implementation has edges. State definition (current digit and remaining length) is the pivot. Most people get the backtracking skeleton right but fumble the boundary checks on next digit arithmetic.
Flipkart asked this. Should I expect it in other tech OAs?+
Only Flipkart is in the data, so no guarantee elsewhere. But the pattern (constrained digit/number generation) is common enough in Amazon and Google assessments. If you see backtracking plus digit constraints, this is your reference solution.
What's the actual trick I'll miss without practice?+
Recognizing that you're building a tree of paths, not exploring a pre-built graph. Each recursive call extends one valid number. The K parameter is a fixed offset, so from digit D you can only go to D+K or D-K if both are in range 0-9. That constraint cuts the branching factor hard.
Should I use DFS or BFS?+
Both work, but DFS (recursive backtracking) is cleaner and uses less memory. You don't need a queue. BFS isn't wrong, just overkill. DFS feels more natural when you're building paths of fixed length N.
What kills most candidates on this problem?+
Off-by-one errors on length checks and forgetting to validate that the next digit stays in 0-9. Some also try to iterate all N-digit numbers and filter, which is inefficient. The clean approach prunes the search space immediately by only exploring valid transitions.
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