package main
import (
"fmt"
)
// maxInt returns the maximum of two integers.
func maxInt(a, b int) int {
if a > b {
return a
}
return b
}
// absInt returns the absolute value of an integer.
func absInt(a int) int {
if a < 0 {
return -a
}
return a
}
// MaxDistanceBetweenNumbers finds the maximum distance (absolute index difference)
// between two numbers in a slice. Returns the distance and true if both numbers exist,
// or 0 and false otherwise.
func MaxDistanceBetweenNumbers(slice []int, num1, num2 int) (int, bool) {
// Variables to track the first and last occurrences of both numbers
first1, last1 := -1, -1
first2, last2 := -1, -1
// Single pass through the slice: O(N) time complexity, O(1) space complexity
for i, current := range slice {
if current == num1 {
if first1 == -1 {
first1 = i // Record the first time num1 appears
}
last1 = i // Continuously update the last time num1 appears
} else if current == num2 {
if first2 == -1 {
first2 = i // Record the first time num2 appears
}
last2 = i // Continuously update the last time num2 appears
}
}
// Edge case: If either number is not present in the slice, return false
if first1 == -1 || first2 == -1 {
return 0, false
}
// The maximum distance is always between the outermost boundaries of the two sets:
// 1. Distance between the first occurrence of num1 and the last occurrence of num2
// 2. Distance between the last occurrence of num1 and the first occurrence of num2
dist1 := absInt(first1 - last2)
dist2 := absInt(last1 - first2)
return maxInt(dist1, dist2), true
}
func main() {
// --- Example Usage ---
slice := []int{2, 3, 7, 3, 3, 4, 8, 8, 8, 11, 9, 1, 3}
number1 := 3
number2 := 8
if result, found := MaxDistanceBetweenNumbers(slice, number1, number2); found {
fmt.Printf("The maximum distance between %d and %d is: %d\n", number1, number2, result)
} else {
fmt.Printf("One or both numbers (%d, %d) were not found in the slice.\n", number1, number2)
}
}
/*
run:
The maximum distance between 3 and 8 is: 7
*/
