Delete the duplicate items in the array (keep the last duplicate elements and ensure the original order of the array)

link
The first 21 topic ;

Method 1 ： Stack

Backward Traversal , For traversal contain Method to determine whether it already exists ;（Stack Inherited from Vector class ;Vector Realized Iterable and Collection Interface ）
Receive and pop up to the new array , Finally, a new array is returned ;
result ： adopt 6/8, Run timeout

    public int[] removeDuplicate (int[] array) {
    
        //  violence 
        // For the last time , Then reverse traversal 
        Stack<Integer> s=new Stack<>();
        for(int i=array.length-1;i>=0;i--){
    
            if(!s.contains(array[i])){
    
                s.push(array[i]);
            }
        }
        // Put the new array 
        int n=s.size();
        int[] r=new int[n];
        // Bomb stack , Just reverse the order 
        for(int j=0;j<n;j++){
    
            r[j]=s.pop();
        }
        return r;
    }

Method 2 ：Set To judge whether or not to repeat + Speed pointer

First traverse in reverse order , Use Set To judge whether or not to repeat , Repeat and set as 0;
Use the speed pointer to delete 0;
The length will be slow Put all the elements of the new array and return ;

public int[] removeDuplicate (int[] array) {
    
        int n=array.length;
        Set<Integer>  s=new HashSet<>();
        //  Reverse traversal , Set the repeated to 0
        for(int i=n-1;i>=0;i--){
    
            if(s.contains(array[i])){
    
               array[i]=0;
            }else{
    
               s.add(array[i]);
            }
        }

        //  The speed pointer deletes 0
        int slow=0;
        int fast=0;
        while(fast<n){
    
            if(array[fast]==0){
    
                fast++;
            }else{
    
                array[slow]=array[fast];
                slow++;
                fast++;
            }
        }

        //0~slow Move to new array 
        int[] r=new int[slow];
        for(int i=0;i<slow;i++){
    
            r[i]=array[i];
        }
        return r;
    }

result ： adopt 6/8