题目

某位用户连续一周登录简书浏览文章，假设他一周浏览文章的天数为一个list，记录为[5,10,2,4,5,3,15]。求解以下两个问题：
（1）该用户在登录几天后可以浏览比当天数量更多的文章数
以第3天为例，他当天浏览了2篇文章，在第4天浏览了4篇文章，那么此时的值应该为1
答案应该是:[1, 5, 1, 1, 2, 1, 0]
（2）该用户在登录几天后可以浏览最多的文章数
以第3天为例，他当天浏览了2篇文章，在第7天浏览了4篇文章，那么此时的值应该为4
答案应该是:[6, 5, 4, 3, 2, 1, 0]

解法

暴力求解

暴力是求解一切算法最好用的方法，这道题暴力求解很容易，直接两层循环解决

#题目1
def nextGreaterElements(nums):
    """
    :type nums: List[int]
    :rtype: List[int]
    """
    nums_length = len(nums)
    res_list = [0 for _ in range(nums_length)]
    res_index = [0 for _ in range(nums_length)]
    for i in range(nums_length):
        for j in range(i+1,nums_length):
            if nums[i] < nums[j]:
                res_list[i] = nums[j]
                res_index[i] = j-i
                break
    return res_list,res_index
print(nextGreaterElements([5,10,2,4,5,3,15])[1])

#题目2
def nextGreaterElements(nums):
    """
    :type nums: List[int]
    :rtype: List[int]
    """
    nums_length = len(nums)
    res_list = [0 for _ in range(nums_length)]
    res_index = [0 for _ in range(nums_length)]
    for i in range(nums_length):
        for j in range(i+1,nums_length):
            if nums[i] < nums[j]:
                res_list[i] = nums[j]
                res_index[i] = j - i
    return res_list,res_index
print(nextGreaterElements([5,10,2,4,5,3,15])[1])

栈求解

栈求解的好处是只用遍历一遍
关于题目1：因为是求解下一个更长时间，所以预先需要设置一个栈存储之后元素，然后通过while不断弹出，而弹出的位置应该从头开始
关于题目2：因为求解最长的时间，因此需要不断的append最大值

#题目1
def nextGreaterElements(nums):
    """
    :type nums: List[int]
    :rtype: List[int]
    """
    nums_length = len(nums)
    res_list = [0 for _ in range(nums_length)]
    res_index = [0 for _ in range(nums_length)]
    for i in range(nums_length):
        print(i)
        stack = list(range(i+1,nums_length))
        print(stack)
        while stack and nums[i]>nums[stack[0]]:
            stack.pop(0)
        res_list[i] = nums[stack[0]] if stack else 0
        res_index[i] = stack[0]-i if stack else 0
    return res_list,res_index
print(nextGreaterElements([5,10,2,4,5,3,15])[1])

#题目2
def nextGreaterElements(nums):
    """
    :type nums: List[int]
    :rtype: List[int]
    """
    nums_length = len(nums)
    res_list = [0 for _ in range(nums_length)]
    res_index = [0 for _ in range(nums_length)]
    for i in range(nums_length-2,-1,-1):
        stack = list(range(i+1,nums_length))
        print(i)
        while (nums[i]>nums[stack[-1]]):
            stack.append(i)
        print(stack)
        res_list[i] = nums[stack[-1]]
        res_index[i] = stack[-1]-i
    return res_list,res_index
print(nextGreaterElements([5,10,2,4,5,3,15])[1])