2441. Largest Positive Integer That Exists With Its Negative

Easy

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

解題

func findMaxK(nums []int) int {
    m := make(map[int]bool)
    
    max:= -1
    
    for _, val := range nums {
        if _,ok := m[-1*val]; ok {
            if val< 0 { 
                if -1*val > max {
                    max = -1*val 
                }
            }
            if val > max { max = val }
        }
        m[val] = true
    }
    
    return max
}