Solution3.go

func minimumOperations(nums []int, start int, goal int) int {
	next := func(x int) []int {
		var res []int
		for _, num := range nums {
			res = append(res, []int{x + num, x - num, x ^ num}...)
		}
		return res
	}
	m1, m2 := map[int]int{start: 0}, map[int]int{goal: 0}
	q1, q2 := []int{start}, []int{goal}
	extend := func() int {
		for i := len(q1); i > 0; i-- {
			x := q1[0]
			q1 = q1[1:]
			step, _ := m1[x]
			for _, y := range next(x) {
				if _, ok := m1[y]; ok {
					continue
				}
				if v, ok := m2[y]; ok {
					return step + 1 + v
				}
				if y >= 0 && y <= 1000 {
					m1[y] = step + 1
					q1 = append(q1, y)
				}
			}
		}
		return -1
	}
	for len(q1) > 0 && len(q2) > 0 {
		if len(q1) > len(q2) {
			m1, m2 = m2, m1
			q1, q2 = q2, q1
		}
		t := extend()
		if t != -1 {
			return t
		}
	}
	return -1
}