longest_switching_slice.go

package main

import "fmt"

func main() {
	fmt.Println(scan([]int{0, 1, 2, 1, 2, 1, 2, 1, 2, 1, 9}))
}

func scan(A []int) int {
	n := len(A)
	if n<=1 {
		return n
	}
	pos := 0
	maxLen := 0
	for pos < n {
		black := pos
		white := pos+1
		for white+2<n && A[black]==A[black+2] && A[white]==A[white+2] {
			black+=2
			white+=2
		}
		if black+2<n && A[black]==A[black+2] {
			black+=2
		}
		end := max(black, white)
		maxLen = max(maxLen, end-pos+1)
		pos = end
	}
	return maxLen
}

func max(a int, b int) int {
	if a > b {
		return a
	}
	return b
}

func check(e error) {
	if e != nil {
		panic(e)
	}
}