Crackingcodinginterview (2.1) removes duplicate elements from the shortlist

Why? Importjava. util. Collections list; importjava. util. Iterator; importjava. util. Collections; importjav

2.1 Write code to remove duplicates from an unsorted linked list. follow up How wocould you solve this problem if a temporary buffer is not allowed? Import java. util. Collections list; import java. util. Iterator; import java. util. Collections; import jav

2.1 Write code to remove duplicates from an unsorted linked list.
FOLLOW UP

How wocould you solve this problem if a temporary buffer is not allowed?

import java.util.LinkedList;import java.util.Iterator;import java.util.Collections;import java.util.Hashtable;public class Solution{//brute-force time complexity:O(n^2) space complexity:O(1)public static void removeDuplicate1(LinkedList
 
   list){for(int i=0;i < list.size()-1;i++)for(int j=i+1;j < list.size();)if(list.get(i) == list.get(j))list.remove(j);elsej++;}//could't keep order time complexity:O(nlogn) space complexity:O(1)public static void removeDuplicate2(LinkedList
  
    list){//sortCollections.sort(list);if(list.size() >= 2){for(int i=0;i < list.size()-1;){if(list.get(i) == list.get(i+1))list.remove(i+1);elsei++;}}}//1.keep order 2.time complexity:O(n) 3.space complexity:O(n): (worst case)public static void removeDuplicate3(LinkedList
   
     list){Hashtable
    
      hash = new Hashtable
     
      ();//lookup hashtable to delete repeat elementsfor(int i=0;i < list.size();){if(hash.containsKey(list.get(i)))list.remove(i);else{hash.put(list.get(i), "");i++;}}}private static void printLinkedList(LinkedList
      
        list){Iterator it = list.iterator();while(it.hasNext()){System.out.print((Integer)it.next()+" ");}System.out.println();}public static void main(String[] args){LinkedList
       
         list = new LinkedList
        
         ();list.add(6);list.add(2);list.add(2);list.add(3);list.add(1);list.add(4);list.add(2);list.add(3);list.add(7);list.add(2);list.add(2);list.add(10);Solution.printLinkedList(list);Solution.removeDuplicate3(list);Solution.printLinkedList(list);}}
        
       
      
     
    
   
  
 

1. brute-force time complexity: O (n ^ 2) space complxity: O (1). The output elements are in the original order.

2. sort: time complexity: O (nlogn) space complexity: O (1). The output element is the sorted result.

3. hashtable: time complexity: O (n) space complexity: O (n). The output elements are in the original order.

Similar Problem: http://blog.csdn.net/u011559205/article/details/38125405