func maxDoubleSliceSum(a []int) int {
	size := len(a)
	if size < 3 {
		return 0
	}

	p1 := make([]int, size)
	p2 := make([]int, size)
	p1[1] = 0
	p2[size-2] = 0

	for i := 2; i < size-1; i++ {
		if v := p1[i-1] + a[i-1]; v > 0 {
			p1[i] = v
		}
		if v := p2[size-i] + a[size-i]; v > 0 {
			p2[size-i-1] = v
		}
	}

	sum := p1[1] + p2[1]
	for i := 1; i < size-1; i++ {
		if s := p1[i] + p2[i]; s > sum {
			sum = s
		}
	}

	return sum
}