C++UCS301
Complexity Lab C++ Setup Visualizer
Practice arena
C++17·2 s·128 MB
SearchingFoundation

First matching index

Find the first zero-based index of target in an unsorted array. Return -1 when target is absent.

Input

  • — The first line contains T.
  • — Each case contains n and target, followed by n integers.

Output

Print the first matching index or -1 for each case.

Technique

left-to-right scan

Target

O(n)

Constraints & sample
  • 1 ≤ n ≤ 200,000
  • The array is not guaranteed to be sorted

Sample input

3
5 7
4 7 1 7 9
4 8
8 2 8 3
3 5
1 2 3

Expected output

1
0
-1
Review the concept

Before you submit

  • Test the smallest valid input and one awkward edge case.
  • Keep the solution within O(n).
  • Match spacing and line breaks exactly before checking 8 hidden cases.
main.cpp
Draft saved locally · 482 / 30,000
Ln 1, Col 1Spaces: 4UTF-8LFC++17

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