# First Unique Number

You have a queue of integers, you need to retrieve the first unique integer in the queue.

Implement the `FirstUnique` class:

1. `FirstUnique(int[] nums)` Initializes the object with the numbers in the queue.
2. `int showFirstUnique()` returns the value of the first unique integer of the queue, and returns -1 if there is no such integer.
3. `void add(int value)` insert value to the queue.

Example 1:

``````Input:
[[[2,3,5]],[],[5],[],[2],[],[3],[]]
Output:
[null,2,null,2,null,3,null,-1]

Explanation:
FirstUnique firstUnique = new FirstUnique([2,3,5]);
firstUnique.showFirstUnique(); // return 2
firstUnique.add(5);            // the queue is now [2,3,5,5]
firstUnique.showFirstUnique(); // return 2
firstUnique.add(2);            // the queue is now [2,3,5,5,2]
firstUnique.showFirstUnique(); // return 3
firstUnique.add(3);            // the queue is now [2,3,5,5,2,3]
firstUnique.showFirstUnique(); // return -1``````

Example 2:

``````Input:
[[[7,7,7,7,7,7]],[],[7],[3],[3],[7],[17],[]]
Output:
[null,-1,null,null,null,null,null,17]

Explanation:
FirstUnique firstUnique = new FirstUnique([7,7,7,7,7,7]);
firstUnique.showFirstUnique(); // return -1
firstUnique.add(7);            // the queue is now [7,7,7,7,7,7,7]
firstUnique.add(3);            // the queue is now [7,7,7,7,7,7,7,3]
firstUnique.add(3);            // the queue is now [7,7,7,7,7,7,7,3,3]
firstUnique.add(7);            // the queue is now [7,7,7,7,7,7,7,3,3,7]
firstUnique.add(17);           // the queue is now [7,7,7,7,7,7,7,3,3,7,17]
firstUnique.showFirstUnique(); // return 17``````

## Solution

A very interesting problem. Use Map to find the duplicate elements. Use Queue to process the input.

### C# Program to understand better

```public class FirstUnique {

Queue<int> queue = new Queue<int>();
Dictionary<int,int> map = new Dictionary<int,int>();

public FirstUnique(int[] nums) {
for(int i=0;i<nums.Length;i++){
}
}

public int ShowFirstUnique() {
while(queue.Count > 0 && map[queue.Peek()] > 1)
queue.Dequeue();

if(queue.Count == 0)
return -1;

return queue.Peek();

}

if(map.ContainsKey(value)){
map[value]++;
}
else{
queue.Enqueue(value);
}
}
}

/**
* Your FirstUnique object will be instantiated and called as such:
* FirstUnique obj = new FirstUnique(nums);
* int param_1 = obj.ShowFirstUnique();