- Difficulty: Easy
- Tags: LeetCode, Easy, Stack, Array, Hash Table, Monotonic Stack, leetcode-496, O(m + n), Mono Stack
Problem
The next greater element of some element x
in an array is the first greater element that is to the right of x
in the same array.
You are given two distinct 0-indexed integer arrays nums1
and nums2
, where nums1
is a subset of nums2
.
For each 0 <= i < nums1.length
, find the index j
such that nums1[i] == nums2[j]
and determine the next greater element of nums2[j]
in nums2
. If there is no next greater element, then the answer for this query is -1
.
Return an array ans
of length nums1.length
such that ans[i]
is the next greater element as described above.
Example 1:
Input: nums1 = [4,1,2], nums2 = [1,3,4,2] Output: [-1,3,-1] Explanation: The next greater element for each value of nums1 is as follows: - 4 is underlined in nums2 = [1,3,4,2]. There is no next greater element, so the answer is -1. - 1 is underlined in nums2 = [1,3,4,2]. The next greater element is 3. - 2 is underlined in nums2 = [1,3,4,2]. There is no next greater element, so the answer is -1.
Example 2:
Input: nums1 = [2,4], nums2 = [1,2,3,4] Output: [3,-1] Explanation: The next greater element for each value of nums1 is as follows: - 2 is underlined in nums2 = [1,2,3,4]. The next greater element is 3. - 4 is underlined in nums2 = [1,2,3,4]. There is no next greater element, so the answer is -1.
Constraints:
1 <= nums1.length <= nums2.length <= 1000
0 <= nums1[i], nums2[i] <= 104
- All integers in
nums1
andnums2
are unique. - All the integers of
nums1
also appear innums2
.
Follow up: Could you find an
O(nums1.length + nums2.length)
solution?