localmax.go

package main

import "fmt"

func main() {
	a := []int{1, 2, 3, 3, 2, 4, 2}
	fmt.Printf("Local max of %v are %v\n", a, localMax(a))
}

func localMax(a []int) []int {
	if len(a) <= 1 {
		return a
	}
	r := []int{}
	// Special cases for start and end
	if a[0] > a[1] {
		r = append(r, a[0])
	}
	if a[len(a)-1] > a[len(a)-2] {
		r = append(r, a[0])
	}
	// O(n) loop to reduce plateaus
	for i := 0; i < len(a)-1; i++ {
		if a[i] == a[i+1] {
			// reslice a to remove
			a = append(a[:i], a[i+1:]...)
		}
	}

	// O(n) loop to find local maxima
	for i, v := range a {
		if i == 0 || i == len(a)-1 {
			continue
		}
		if v > a[i-1] && v > a[i+1] {
			r = append(r, v)
		}
	}
	return r
}