- Difficulty: Hard
- Tags: LeetCode, Hard, Stack, Array, Binary Search, Sorting, Monotonic Stack, Heap (Priority Queue), leetcode-2454, O(n), Mono Stack
Problem
You are given a 0-indexed array of non-negative integers nums
. For each integer in nums
, you must find its respective second greater integer.
The second greater integer of nums[i]
is nums[j]
such that:
j > i
nums[j] > nums[i]
- There exists exactly one index
k
such thatnums[k] > nums[i]
andi < k < j
.
If there is no such nums[j]
, the second greater integer is considered to be -1
.
- For example, in the array
[1, 2, 4, 3]
, the second greater integer of1
is4
,2
is3
, and that of3
and4
is-1
.
Return an integer array answer
, where answer[i]
is the second greater integer of nums[i]
.
Example 1:
Input: nums = [2,4,0,9,6] Output: [9,6,6,-1,-1] Explanation: 0th index: 4 is the first integer greater than 2, and 9 is the second integer greater than 2, to the right of 2. 1st index: 9 is the first, and 6 is the second integer greater than 4, to the right of 4. 2nd index: 9 is the first, and 6 is the second integer greater than 0, to the right of 0. 3rd index: There is no integer greater than 9 to its right, so the second greater integer is considered to be -1. 4th index: There is no integer greater than 6 to its right, so the second greater integer is considered to be -1. Thus, we return [9,6,6,-1,-1].
Example 2:
Input: nums = [3,3] Output: [-1,-1] Explanation: We return [-1,-1] since neither integer has any integer greater than it.
Constraints:
1 <= nums.length <= 105
0 <= nums[i] <= 109