# 2465. Number of Distinct Averages

Easy
You are given a 0-indexed integer array `nums` of even length.
As long as `nums` is not empty, you must repetitively:
• Find the minimum number in `nums` and remove it.
• Find the maximum number in `nums` and remove it.
• Calculate the average of the two removed numbers.
The average of two numbers `a` and `b` is `(a + b) / 2`.
• For example, the average of `2` and `3` is `(2 + 3) / 2 = 2.5`.
Return the number of distinct averages calculated using the above process.
Note that when there is a tie for a minimum or maximum number, any can be removed.
Example 1:
Input: nums = [4,1,4,0,3,5]
Output: 2
Explanation:
1. Remove 0 and 5, and the average is (0 + 5) / 2 = 2.5. Now, nums = [4,1,4,3].
2. Remove 1 and 4. The average is (1 + 4) / 2 = 2.5, and nums = [4,3].
3. Remove 3 and 4, and the average is (3 + 4) / 2 = 3.5.
Since there are 2 distinct numbers among 2.5, 2.5, and 3.5, we return 2.
Example 2:
Input: nums = [1,100]
Output: 1
Explanation:
There is only one average to be calculated after removing 1 and 100, so we return 1.
Constraints:
• `2 <= nums.length <= 100`
• `nums.length` is even.
• `0 <= nums[i] <= 100`

### 解題

Runtime: 0 ms, faster than 100%
Memory Usage: 1.9 MB, less than 91.22%
func distinctAverages(nums []int) int {
sort.Ints(nums)
left := 0
right := len(nums) - 1
m := make(map[float64]bool)
for left < right {
m[float64(nums[left] + nums[right]) / float64(2)] = true
left++
right--
}
return len(m)
}