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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

just  write the code  by myself,  but  didnt test it :

package Amazoninterview;
. 鍥磋鎴戜滑@1point 3 acres
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedList;. Waral 鍗氬鏈夋洿澶氭枃绔,
import java.util.List;
import java.util.Map;

/*. from: 1point3acres.com/bbs
* 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.
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 {. 1point 3acres 璁哄潧

        public static void main(String[] args) {
               
        }
        public static Map<String,Integer> getRecommedations(String userId){
                List<String> friends = getFriendsListForUser(userId);
                HashSet<String> myCourses = getCoursesForUser( userId);
                if(friends ==null || friends.size() ==0 )
                        return null;
                if(myCourses == null) 鏉ユ簮涓浜.涓夊垎鍦拌鍧.
                        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)). 鍥磋鎴戜滑@1point 3 acres
                                        continue;
                                if(recommendMap.get(course)!=null){
                                        recommendMap.put(course, recommendMap.get(course)+1);
                                }
                                else{
                                        recommendMap.put(course,1);
                                }. 鐗涗汉浜戦泦,涓浜╀笁鍒嗗湴
                        }
                }
                if(recommendMap !=null && recommendMap.size() >0)
                        return sortByValue(recommendMap);
                return null;
        }
        . 鐗涗汉浜戦泦,涓浜╀笁鍒嗗湴
        public static Map sortByValue(Map unsortMap) {          鏉ユ簮涓浜.涓夊垎鍦拌鍧.
                List list = new LinkedList(unsortMap.entrySet());. 鐣欏鐢宠璁哄潧-涓浜╀笁鍒嗗湴
         
                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();) {. From 1point 3acres bbs
                        Map.Entry entry = (Map.Entry) it.next();
                        sortedMap.put(entry.getKey(), entry.getValue());
                }
                return sortedMap;
        }. 鐗涗汉浜戦泦,涓浜╀笁鍒嗗湴
       
        //giving function
        . Waral 鍗氬鏈夋洿澶氭枃绔,
        public static  List<String> getFriendsListForUser(String userId){. visit 1point3acres.com for more.
                return null;       
        }
        public static HashSet<String>getCoursesForUser(String userId){. From 1point 3acres bbs
                return null;
        }
}

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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