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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 :
.鏈枃鍘熷垱鑷1point3acres璁哄潧
package amazoninterview;. 鍥磋鎴戜滑@1point 3 acres

import java.util.Collections;
import java.util.Comparator;. 鐗涗汉浜戦泦,涓浜╀笁鍒嗗湴
import java.util.HashMap; 鏉ユ簮涓浜.涓夊垎鍦拌鍧.
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedList;.鐣欏璁哄潧-涓浜-涓夊垎鍦
import java.util.List;
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.
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
*/.1point3acres缃
public class Recommender {.1point3acres缃

        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)
                        myCourses = new HashSet<String>();
                HashMap<String,Integer> recommendMap = new HashMap<String,Integer>();. 1point3acres.com/bbs
                for(String friend:friends){. from: 1point3acres.com/bbs
                        HashSet<String> friendCourseList = getCoursesForUser( friend);. 鍥磋鎴戜滑@1point 3 acres
                        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);
                                }
                        }
                }. from: 1point3acres.com/bbs
                if(recommendMap !=null && recommendMap.size() >0)
                        return sortByValue(recommendMap);
                return null;
        }
       
        public static Map sortByValue(Map unsortMap) {         
                List list = new LinkedList(unsortMap.entrySet());
         . From 1point 3acres bbs
                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();. 1point 3acres 璁哄潧
                for (Iterator it = list.iterator(); it.hasNext();) {
                        Map.Entry entry = (Map.Entry) it.next();. 鍥磋鎴戜滑@1point 3 acres
                        sortedMap.put(entry.getKey(), entry.getValue());. 鍥磋鎴戜滑@1point 3 acres
                }
                return sortedMap;
        }
       
        //giving function
       
        public static  List<String> getFriendsListForUser(String userId){
                return null;        鏉ユ簮涓浜.涓夊垎鍦拌鍧.
        }
        public static HashSet<String>getCoursesForUser(String userId){
                return null;
        }
}

hopfully  it helps



daykills 发表于 2016-2-24 09:43:23 | 显示全部楼层
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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