Sum Signed Values in Java with IntStream
Combine absolute values and matching boolean signs with IntStream. Check cancellation, all-negative input, int bounds, and the equal-length array contract.
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algorithms10
Practical notes on Java, Spring, testing, and software engineering, with working examples and source references.
Generate an x-Spaced Sequence in Java: Promote Before Multiplication
Build n values from x through x*n with IntStream. Explain why mapToLong alone does not prevent int overflow, and check positive, negative, and zero steps.
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Remove Adjacent Duplicate Pairs in Java with an ArrayDeque Stack
Reduce adjacent equal-character pairs with a stack. Explain the prefix invariant, cascading removal, million-character boundaries, and time and space costs.
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Find the Missing Runner in Java with Name Frequencies
Subtract completion counts from participant counts with HashMap. Handle duplicate names without Set subtraction and explain the one-missing-runner contract.
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Sort Failure Rates in Java: Denominators, Ties, and Long Products
Count stopped and reached players, sort exact rates with long cross-products, and handle unreachable stages, full completion, and stage-number tie-breaking.
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Java Ponketmon: Why the Answer Is min(Distinct Types, N/2)
Count distinct types with HashSet and prove the selection bound is achievable. Distinguish the maximum type count from constructing an actual selection.
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Java New ID Recommendation: Normalization Order and Truncation
Implement ID normalization with an Optional chain and a loop. Check dot collapsing, empty input after filtering, truncation cleanup, padding, and locale independence.
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Java Array Dot Product: IntStream and Integer Bounds
Multiply matching array elements and sum them with IntStream. Understand signs, int bounds, and why wider multiplication must promote operands before overflow.
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Convert English Digit Words in Java with String.replace
Normalize valid mixtures of digits and zero-to-nine words using literal replacement. Distinguish replace from replaceAll and explain integer bounds and scope.
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Java LRU Cache: Use Access Order in LinkedHashMap
Simulate an LRU cache with access-ordered LinkedHashMap. Check hit refresh, eviction, case-insensitive keys, zero capacity, and the model’s cost assumptions.
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