README.md

2441. Largest Positive Integer That Exists With Its Negative

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

Solutions (Rust)

1. Solution

use std::collections::HashSet;

impl Solution {
    pub fn find_max_k(nums: Vec<i32>) -> i32 {
        let nums_set = nums.iter().collect::<HashSet<_>>();

        *nums
            .iter()
            .filter(|&&x| nums_set.contains(&-x))
            .max()
            .unwrap_or(&-1)
    }
}