一天两道力扣（2）

# 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 middleNode(self, head):
        slow = fast = head
        while fast and fast.next:
            fast = fast.next.next
            slow = slow.next
        return slow
    def reverseList(self, head):
        pre, cur = None, head
        while cur:
            nxt = cur.next
            cur.next = pre
            pre = cur
            cur = nxt
        return pre

    def isPalindrome(self, head):
        mid = self.middleNode(head)
        head2 = self.reverseList(mid)
        while head2:
            if head.val != head2.val:
                return False
            head = head.next
            head2 = head2.next
        return True
        

解析：先找到中间位置，然后从中间反转， 再对比

class Solution(object):
    def dailyTemperatures(self, temperatures):
        length = len(temperatures)
        ans = [0] * length
        stack = []
        for i in range(length):
            temperature = temperatures[i]
            while stack and temperature > temperatures[stack[-1]]:
                pre_index = stack.pop()
                ans[pre_index] = i - pre_index
            stack.append(i)
        return ans

解析：单调栈里面存的是下标，遇到大的就弹出来且记录，不大就继续存着