496.NextGreaterElementI.py

"""
    You are given two arrays (without duplicates) nums1 and nums2 where nums1’s 
    elements are subset of nums2. Find all the next greater numbers for nums1's 
    elements in the corresponding places of nums2.
    The Next Greater Number of a number x in nums1 is the first greater number 
    to its right in nums2. If it does not exist, output -1 for this number.

    Example:
    Input: nums1 = [4,1,2], nums2 = [1,3,4,2].
    Output: [-1,3,-1]
    Explanation:
                - For number 4 in the first array, you cannot find the next 
                  greater number for it in the second array, so output -1.
                - For number 1 in the first array, the next greater number for 
                  it in the second array is 3.
                - For number 2 in the first array, there is no next greater 
                  number for it in the second array, so output -1.

    Note:
    - All elements in nums1 and nums2 are unique.
    - The length of both nums1 and nums2 would not exceed 1000.    
"""
#Difficulty: Easy
#17 / 17 test cases passed.
#Runtime: 116 ms
#Memory Usage: 13.8 MB

#Runtime: 116 ms, faster than 14.67% of Python3 online submissions for Next Greater Element I.
#Memory Usage: 13.8 MB, less than 94.31% of Python3 online submissions for Next Greater Element I.

class Solution:
    def nextGreaterElement(self, nums1: List[int], nums2: List[int]) -> List[int]:
        l1 = len(nums1)
        l2 = len(nums2)
        for i in range(l1):
            j = nums2.index(nums1[i])
            while True:
                if nums2[j] > nums1[i]:
                    nums1[i] = nums2[j]
                    break
                if j == l2 - 1:
                    nums1[i] = -1
                    break
                j += 1
        return nums1