func findUnsortedSubarray(nums []int) int {
	n := len(nums)
	sorted := make([]int, n)
	copy(sorted, nums)
	sort.Ints(sorted)
	l, r := 0, n-1
	for ; l < n && nums[l] == sorted[l]; l++ {
	}
	if l == n {
		return 0
	}
	for ; nums[r] == sorted[r]; r-- {
	}
	return r - l + 1
}