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
}