package main
import (
"errors"
"fmt"
"math"
)
/*
FindMinimumDistance returns the minimum distance between two target values.
Returns:
- The minimum distance between target1 and target2.
- -1 if no valid pair exists.
Time Complexity: O(n)
Space Complexity: O(1)
*/
func FindMinimumDistance(numbers []int, target1, target2 int) (int, error) {
if numbers == nil {
return -1, errors.New("numbers cannot be nil")
}
// Handle the special case where both targets are the same.
if target1 == target2 {
return findMinimumDistanceForDuplicates(numbers, target1), nil
}
lastSeenIndex := -1
minDistance := math.MaxInt
for currentIndex, currentValue := range numbers {
// Ignore values that are not one of the targets.
if currentValue != target1 && currentValue != target2 {
continue
}
/*
If we've previously seen one target and the current
value is the other target, update the minimum distance.
*/
if lastSeenIndex >= 0 && currentValue != numbers[lastSeenIndex] {
distance := currentIndex - lastSeenIndex
if distance < minDistance {
minDistance = distance
}
}
// Remember the most recent occurrence.
lastSeenIndex = currentIndex
}
if minDistance == math.MaxInt {
return -1, nil
}
return minDistance, nil
}
/*
findMinimumDistanceForDuplicates finds the minimum distance
between consecutive occurrences of the same value.
*/
func findMinimumDistanceForDuplicates(
numbers []int,
target int,
) int {
previousIndex := -1
minDistance := math.MaxInt
for currentIndex, currentValue := range numbers {
if currentValue != target {
continue
}
if previousIndex >= 0 {
distance := currentIndex - previousIndex
if distance < minDistance {
minDistance = distance
}
}
previousIndex = currentIndex
}
if minDistance == math.MaxInt {
return -1
}
return minDistance
}
func main() {
numbers := []int{2, 3, 7, 3, 3, 4, 8, 8, 8, 11, 9, 1, 3,
}
distance, err := FindMinimumDistance(numbers, 3, 8)
if err != nil {
fmt.Println("Error:", err)
return
}
if distance >= 0 {
fmt.Printf(
"Minimum distance between 3 and 8: %d\n",
distance,
)
} else {
fmt.Println("No valid pair found.")
}
}
/*
run:
Minimum distance between 3 and 8: 2
*/
