2441. Largest Positive Integer That Exists With Its Negative

Problem

Given an integer array nums that does not contain any zeros, find the largest positive integer k such that -k also exists in the array.

Return the positive integer k. If there is no such integer, return -1.

  Example 1:

Input: nums = [-1,2,-3,3]
Output: 3
Explanation: 3 is the only valid k we can find in the array.

Example 2:

Input: nums = [-1,10,6,7,-7,1]
Output: 7
Explanation: Both 1 and 7 have their corresponding negative values in the array. 7 has a larger value.

Example 3:

Input: nums = [-10,8,6,7,-2,-3]
Output: -1
Explanation: There is no a single valid k, we return -1.

Constraints:

• 1 <= nums.length <= 1000
• -1000 <= nums[i] <= 1000
• nums[i] != 0

Solution (Java)

class Solution {
    public int findMaxK(int[] nums) {
        HashSet<Integer> st = new HashSet<>();
        for (int i : nums) st.add(i);
        int res = -1;
        for (int p : nums)
             if (p > 0 && st.contains(-p)) res = Math.max(res, p);
        return res;
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).