# LeetCode 1133. Largest Unique Number

## Description

https://leetcode.com/problems/largest-unique-number/

Given an array of integers `A`, return the largest integer that only occurs once.

If no integer occurs once, return -1.

Example 1:

```Input: [5,7,3,9,4,9,8,3,1]
Output: 8
Explanation:
The maximum integer in the array is 9 but it is repeated. The number 8 occurs only once, so it's the answer.
```

Example 2:

```Input: [9,9,8,8]
Output: -1
Explanation:
There is no number that occurs only once.
```

Note:

1. `1 <= A.length <= 2000`
2. `0 <= A[i] <= 1000`

## Explanation

Count, sort, and find out the result.

## Python Solution

``````class Solution:
def largestUniqueNumber(self, A: List[int]) -> int:
counter = {}

for num in A:
counter[num] = counter.get(num, 0) + 1

results = []
for key, value in counter.items():
if value == 1:
results.append(key)

if not results:
return -1

results = sorted(results)

return results[-1]``````
• Time Complexity: O(N)
• Space Complexity: O(Nlog(N))