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

Implement the FirstUnique class:

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

Example 1:

Input: 
["FirstUnique","showFirstUnique","add","showFirstUnique","add","showFirstUnique","add","showFirstUnique"]
[[[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: 
["FirstUnique","showFirstUnique","add","add","add","add","add","showFirstUnique"]
[[[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

Example 3:

Input: 
["FirstUnique","showFirstUnique","add","showFirstUnique"]
[[[809]],[],[809],[]]
Output: 
[null,809,null,-1]

Explanation: 
FirstUnique firstUnique = new FirstUnique([809]);
firstUnique.showFirstUnique(); // return 809
firstUnique.add(809);          // the queue is now [809,809]
firstUnique.showFirstUnique(); // return -1

 

Constraints:

1 <= nums.length <= 10^5
1 <= nums[i] <= 10^8
1 <= value <= 10^8
At most 50000 calls will be made to showFirstUnique and add.

Solution：

import "container/list"

type FirstUnique struct {
    Dict *map[int]int
    UQ  *list.List 
    
}


func Constructor(nums []int) FirstUnique {
    instance := FirstUnique{
        Dict: &map[int]int{},
        UQ: list.New(), 
    }
    for i := 0; i < len(nums); i++ {
        target := (nums)[i]
        instance.Add(target)
    }
    return instance
}


func (this *FirstUnique) ShowFirstUnique() int {
    
    e := (*(this.UQ)).Front()
    if e != nil {
        return  (e.Value).(int)
    }
    return -1
}


func (this *FirstUnique) Add(value int)  {
    (*(this.Dict))[value] += 1
    switch {
        case  (*(this.Dict))[value] == 1: 
            (*(this.UQ)).PushBack(value)

        case  (*(this.Dict))[value] == 2:
            for e := (*(this.UQ)).Front(); e != nil; e = e.Next() {
                if (e.Value.(int) == value) {
                    (*(this.UQ)).Remove(e)
                }
            }
        default:
            break;
    }

}


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