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Amazon OA新题 用户-好友-好友推荐的课程 code

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laonong15 发表于 2016-2-24 04:53:48 | 显示全部楼层 |阅读模式

2016(1-3月) 码农类 本科 全职@Amazon - Other - 技术电面 |Other其他

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the original  link  is :
http://www.1point3acres.com/bbs/ ... p;page=1#pid2230193
.1point3acres缃
just  write the code  by myself,  but  didnt test it :. 鐗涗汉浜戦泦,涓浜╀笁鍒嗗湴

package Amazoninterview;

import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;. Waral 鍗氬鏈夋洿澶氭枃绔,
import java.util.HashSet;. 鐣欏鐢宠璁哄潧-涓浜╀笁鍒嗗湴
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedList;. 鐗涗汉浜戦泦,涓浜╀笁鍒嗗湴
import java.util.List;. Waral 鍗氬鏈夋洿澶氭枃绔,
import java.util.Map;

/*
* 1. Use a HashSet<String> courseSet and store all the courses made by the user
2. Keep one more HashMap<Course, Integer> recommendation
2. Get the list of Friends for the user
3. Iterate through the friends list and in that find the courses selected by the friend
4. If the course present in courseSet, omit else, put it in recommendation and increment it's count by 1. .鏈枃鍘熷垱鑷1point3acres璁哄潧
5. After all the friends are evaluated. Sort the recommendation by it's value,  

t's O(n) Space  because n is the number of courses selected in total by all your friends.
A  it would be O(k*p) where k is the number of friends and p is the number of courses a friend selects
*/
public class Recommender {
.鏈枃鍘熷垱鑷1point3acres璁哄潧
        public static void main(String[] args) { 鏉ユ簮涓浜.涓夊垎鍦拌鍧.
               
        }
        public static Map<String,Integer> getRecommedations(String userId){. more info on 1point3acres.com
                List<String> friends = getFriendsListForUser(userId);
                HashSet<String> myCourses = getCoursesForUser( userId);
                if(friends ==null || friends.size() ==0 )
                        return null;
                if(myCourses == null)
                        myCourses = new HashSet<String>();
                HashMap<String,Integer> recommendMap = new HashMap<String,Integer>();
                for(String friend:friends){
                        HashSet<String> friendCourseList = getCoursesForUser( friend);
                        for(String course:friendCourseList){
                                if(myCourses.contains(course))
                                        continue;
                                if(recommendMap.get(course)!=null){
                                        recommendMap.put(course, recommendMap.get(course)+1);
                                }
                                else{
                                        recommendMap.put(course,1);
.1point3acres缃                                }. more info on 1point3acres.com
                        }
                }
                if(recommendMap !=null && recommendMap.size() >0)
                        return sortByValue(recommendMap);. 鐣欏鐢宠璁哄潧-涓浜╀笁鍒嗗湴
                return null;
        }
       
        public static Map sortByValue(Map unsortMap) {         
                List list = new LinkedList(unsortMap.entrySet());
         
                Collections.sort(list, new Comparator() {
                        public int compare(Object o1, Object o2) {
                                return ((Comparable) ((Map.Entry) (o1)).getValue())
                                                        .compareTo(((Map.Entry) (o2)).getValue());
                        }
                });
         
                Map sortedMap = new LinkedHashMap();
                for (Iterator it = list.iterator(); it.hasNext();) {
                        Map.Entry entry = (Map.Entry) it.next();
                        sortedMap.put(entry.getKey(), entry.getValue());
                }.1point3acres缃
                return sortedMap;. from: 1point3acres.com/bbs
        }
        . more info on 1point3acres.com
        //giving function
       
        public static  List<String> getFriendsListForUser(String userId){
                return null;       
        }. from: 1point3acres.com/bbs
        public static HashSet<String>getCoursesForUser(String userId){
                return null;
        }
}.鏈枃鍘熷垱鑷1point3acres璁哄潧

hopfully  it helps



daykills 发表于 2016-2-24 09:43:23 | 显示全部楼层
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Warald_一亩三分地
我面的也是这题...你后来需要搞个半小时的电话面谈吗?
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