Day5 leetcode Next Greater Element 下一个更大的元素

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 1:

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.

Example 2:

Input: nums1 = [2,4], nums2 = [1,2,3,4].

Output: [3,-1]

Explanation:

    For number 2 in the first array, the next greater number for it in the second array is 3.

    For number 4 in the first array, there is no next greater number for it in the second array, so

Note:


All elements in nums1 and nums2 are unique.
The length of both nums1 and nums2 would not exceed 1000.
 
中文解释下：
有2个数组（列表） num1,和num2,

nums1 = [4,1,2], nums2 = [1,3,4,2].
 
nums1是num2的子集
 
然后在nums1中每个元素，在num2中找到第一个比它大的元素，比如nums1中第一个是4，在nums2中没有比4更大的，所以返回的是-1，nums第二个是1，在nums2中第一个比1大的是3，所以返回的是3，第三个的是2，nums2中第一个比2大的数是3，所以返回的是3
所以上面的结果需要返回：
[-1,3,3]