Example 1 · empty
- Arguments
- values
[]
target0
- Expected return
-1
Test data
- Input
{"values":[],"target":0}- Expected output
-1
First target index
First target index
EasyYour task
- Find the first occurrence of target in a sorted array.
- Return its smallest matching index, or -1 if target is absent.
- Return the index, not the value.
Required API
- FirstTargetIndex
func FirstTargetIndex(values []int, target int) int
Behavior
- The array is in nondecreasing order and may contain duplicates.
- The input is valid: 0–1,000 integers, with every value and target between -100,000 and 100,000 inclusive.
- Leave the input unchanged and keep separate calls independent.
- Aim for O(log n) time and O(1) extra space using only the standard library.
- Explain which interval can still contain the first match.
Notes and example notation
Examples use {"values": [...], "target": ...}.
Examples
The runner calls your functions directly; you do not need to parse JSON.
Example 2 · first match
- Arguments
- values
[ 1, 2, 2, 2, 5 ]
target2
- Expected return
1
Test data
- Input
{"values":[1,2,2,2,5],"target":2}- Expected output
1
Example 3 · missing
- Arguments
- values
[ 1, 3, 7 ]
target4
- Expected return
-1
Test data
- Input
{"values":[1,3,7],"target":4}- Expected output
-1
Example 4 · last match
- Arguments
- values
[ -4, 0, 8 ]
target8
- Expected return
2
Test data
- Input
{"values":[-4,0,8],"target":8}- Expected output
2
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