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+# 2058. Find the Minimum and Maximum Number of Nodes Between Critical Points
+
+"""
+a critical point in a linked list is defined as either a local maxima or a
+local minima. anode is a local maxima if the current node has a value
+strictly greater than the previous node and the next node. a node is a minima
+if the current node has a value strictly smaller than the previous node and
+the next node. note that a node can only be a local maxima/minima if there
+exists both a previous node and a next node. given a linked list 'head',
+return an array of length 2 container '[min_distance, max_distance]' where
+'min_distance' is the minimum distance between any two distinct nodes and
+oppositely true for 'max_distance'. if there are fewer than two critical
+points, return '[-1, -1]'
+"""
+
+
+# Definition for singly-linked list.
+class ListNode(object):
+ def __init__(self, val=0, next=None):
+ self.val = val
+ self.next = next
+
+
+class Solution(object):
+ def nodesBetweenCriticalPoints(self, head):
+ """
+ :type head: Optional[ListNode]
+ :rtype: List[int]
+ """
+ crit, crit_pt, prev = 0, [], head.val
+ while head.next:
+ if (prev - head.val) * (head.val - head.next.val) < 0:
+ crit_pt.append(crit)
+ prev, head = head.val, head.next
+ crit += 1
+ n = len(crit_pt)
+ if n < 2:
+ return [-1, -1]
+ mn = min((crit_pt[i] - crit_pt[i - 1] for i in range(1, n)))
+ mx = crit_pt[-1] - crit_pt[0]
+ return [mn, mx]