Zenefits Interview Misc


http://www.1point3acres.com/bbs/thread-145166-1-1.html
一个matrix, 1代表机器人,0代表通路,x代表路障,求到所有机器人距离和最小的一点
需要注意的是机器人本身也是通路的一部分,可以通过他到达其他机器人,甚至最小点
也可以和机器人在同一个点上。
另外如果被路障围起来的点不能被算进来

面试时先介绍一下自己,问几个行为问题,然后讲题目思路,这样就差不多过了半小时,后面写程序时间有点紧,
所以介绍时尽量简短一点。
说思路的时候,说了bfs, dfs,面试官说bfs好,又问内存用多少,答O(m*n), 要求节省内存,但我没有想出来不用queue做bfs,
现在想内存最多是O(m + n)应该已经很好了。不过后来又用了一个存距离和判断访问过的二维数组,所以应该还是需要O(m*n),
不知道有什么办法节省。后来面试官没有深究。
基本思路就是找到一个机器人位置,从这点开始bfs, 把所有点到这个机器人的距离加到dis数组,最后扫一遍看看谁距离最短就返回
这点。

/*//problem: robot merge point
//input:
//robot: 1
//obstacle: X
[
0   0   0   M   1
0   1   X   0   0
0   X   0   0   0
0   0   0   1   0
0   0   0   0   0
//output:
//best merge point: M
3 + 1 + 3 = 7
Definition: Best merge point: minimal sum of path num between robots and merge point*/

这个题最优解法就是以每个robot为源点都做一遍bfs,然后把和加起来找个最小的
http://www.1point3acres.com/bbs/thread-145290-1-1.html
1. Longest Chain
给定一个词典, 对于里面单词删掉任何一个字母,如果新单词还在词典里,就形成一个 chain:old word -> new word, 求最长长
比如给List<String> dict = {a,ba,bca,bda,bdca} 最长是4:bdca->bda->ba->a;


我用的map<Integer (length),set<String>> 先字典里的词放到map里,然后从最长的词的set里开始recursive call,直到搜到长度是1的里面或者找不到了,int变量记录最长结果。

        int longest_chain(String[] w) {
        int len = w.length;
        if (len == 0) return 0;
        Queue<String> cBuf = new LinkedList();
        Map<Integer, Set<String>> allWd = new HashMap();
        int maxLen = 0;
        int maxCLen = 0;
        // find the longest length of strings in w
        for (int i = 0; i < w.length; i++){
            int curLen = w[i].length();
            maxLen = Math.max(maxLen, curLen);
            if (allWd.containsKey(curLen)) allWd.get(curLen).add(w[i]);
            else{
                Set<String> curSet = new HashSet();
                curSet.add(w[i]);
                allWd.put(curLen, curSet);
            }
        }
        // search from certain length of words
        for (int i = maxLen; i > maxCLen; i--){
            cBuf = new LinkedList(allWd.get(i));
            // start from initial set of words to search for chain
            int clen = 0;
            while (!cBuf.isEmpty()){
                clen++;
                Set<String> nextSet = allWd.get(i - clen);
                if (nextSet == null) break;
                int count = cBuf.size();
                for (int h = 0; h < count; h++){
                    String t = cBuf.poll();
                    // get next string by deleting one letter
                    for (int l = 0; l < t.length(); l++){
                        String tt = t.substring(0, l) + t.substring(l + 1);
                        if (nextSet.contains(tt)){
                            cBuf.offer(tt);
                            nextSet.remove(tt);
                        }
                    }
                }
            }
            maxCLen = Math.max(maxCLen, clen);
            i -= Math.max(clen - 1, 0);
        }
        return maxCLen;
    }

http://www.1point3acres.com/bbs/thread-147870-1-1.html
一道是比较绕的kth permutation,一道是分数化简,主要考greatest common divsor

find lake。想必大家应该耳熟能详。0表示水,1表示陆地,小哥一直强调lake是只被同一个island围绕的水,边界不算lake。后来冷静了想想,如果是lake的话,也只能被同一个island包围吧。
http://www.jiuzhang.com/qa/19/
第一步,从边缘处将所有的0用bfs遍历,标记成1,即把所以的大海变成陆地。
第二步,从边缘处将所有的1(包括大海变过来的1)用bfs遍历,标记成2,即去掉所有的陆地。(这样可以去掉大海中的小岛)
第三部,再对剩下所有为1的小岛进行遍历,找到一个,结果加一。(剩下的0全部为湖,剩下的1全部为湖中小岛)

设计data structure,里面含有两个函数 add(int x),表示值x出现。 int rank(int y), 返回当前时刻比y小的所有值,大家参见这个题目:http://www.lintcode.com/en/probl ... mber-before-itself/我用segment tree做的,不满意。说spatial cost太大。然后说可以用binary tree with count做(我是看了这篇文章的想法 http://www.geeksforgeeks.org/cou ... ents-on-right-side/),但是烙印不置可否。

1+2-3/4*5"  算结果,老题了。follow up是加上括号以后怎么处理,没写code。然后recurring decimal,没写完code



Labels

LeetCode (1432) GeeksforGeeks (1122) LeetCode - Review (1067) Review (882) Algorithm (668) to-do (609) Classic Algorithm (270) Google Interview (237) Classic Interview (222) Dynamic Programming (220) DP (186) Bit Algorithms (145) POJ (141) Math (137) Tree (132) LeetCode - Phone (129) EPI (122) Cracking Coding Interview (119) DFS (115) Difficult Algorithm (115) Lintcode (115) Different Solutions (110) Smart Algorithm (104) Binary Search (96) BFS (91) HackerRank (90) Binary Tree (86) Hard (79) Two Pointers (78) Stack (76) Company-Facebook (75) BST (72) Graph Algorithm (72) Time Complexity (69) Greedy Algorithm (68) Interval (63) Company - Google (62) Geometry Algorithm (61) Interview Corner (61) LeetCode - Extended (61) Union-Find (60) Trie (58) Advanced Data Structure (56) List (56) Priority Queue (53) Codility (52) ComProGuide (50) LeetCode Hard (50) Matrix (50) Bisection (48) Segment Tree (48) Sliding Window (48) USACO (46) Space Optimization (45) Company-Airbnb (41) Greedy (41) Mathematical Algorithm (41) Tree - Post-Order (41) ACM-ICPC (40) Algorithm Interview (40) Data Structure Design (40) Graph (40) Backtracking (39) Data Structure (39) Jobdu (39) Random (39) Codeforces (38) Knapsack (38) LeetCode - DP (38) Recursive Algorithm (38) String Algorithm (38) TopCoder (38) Sort (37) Introduction to Algorithms (36) Pre-Sort (36) Beauty of Programming (35) Must Known (34) Binary Search Tree (33) Follow Up (33) prismoskills (33) Palindrome (32) Permutation (31) Array (30) Google Code Jam (30) HDU (30) Array O(N) (29) Logic Thinking (29) Monotonic Stack (29) Puzzles (29) Code - Detail (27) Company-Zenefits (27) Microsoft 100 - July (27) Queue (27) Binary Indexed Trees (26) TreeMap (26) to-do-must (26) 1point3acres (25) GeeksQuiz (25) Merge Sort (25) Reverse Thinking (25) hihocoder (25) Company - LinkedIn (24) Hash (24) High Frequency (24) Summary (24) Divide and Conquer (23) Proof (23) Game Theory (22) Topological Sort (22) Lintcode - Review (21) Tree - Modification (21) Algorithm Game (20) CareerCup (20) Company - Twitter (20) DFS + Review (20) DP - Relation (20) Brain Teaser (19) DP - Tree (19) Left and Right Array (19) O(N) (19) Sweep Line (19) UVA (19) DP - Bit Masking (18) LeetCode - Thinking (18) KMP (17) LeetCode - TODO (17) Probabilities (17) Simulation (17) String Search (17) Codercareer (16) Company-Uber (16) Iterator (16) Number (16) O(1) Space (16) Shortest Path (16) itint5 (16) DFS+Cache (15) Dijkstra (15) Euclidean GCD (15) Heap (15) LeetCode - Hard (15) Majority (15) Number Theory (15) Rolling Hash (15) Tree Traversal (15) Brute Force (14) Bucket Sort (14) DP - Knapsack (14) DP - Probability (14) Difficult (14) Fast Power Algorithm (14) Pattern (14) Prefix Sum (14) TreeSet (14) Algorithm Videos (13) Amazon Interview (13) Basic Algorithm (13) Codechef (13) Combination (13) Computational Geometry (13) DP - Digit (13) LCA (13) LeetCode - DFS (13) Linked List (13) Long Increasing Sequence(LIS) (13) Math-Divisible (13) Reservoir Sampling (13) mitbbs (13) Algorithm - How To (12) Company - Microsoft (12) DP - Interval (12) DP - Multiple Relation (12) DP - Relation Optimization (12) LeetCode - Classic (12) Level Order Traversal (12) Prime (12) Pruning (12) Reconstruct Tree (12) Thinking (12) X Sum (12) AOJ (11) Bit Mask (11) Company-Snapchat (11) DP - Space Optimization (11) Dequeue (11) Graph DFS (11) MinMax (11) Miscs (11) Princeton (11) Quick Sort (11) Stack - Tree (11) 尺取法 (11) 挑战程序设计竞赛 (11) Coin Change (10) DFS+Backtracking (10) Facebook Hacker Cup (10) Fast Slow Pointers (10) HackerRank Easy (10) Interval Tree (10) Limited Range (10) Matrix - Traverse (10) Monotone Queue (10) SPOJ (10) Starting Point (10) States (10) Stock (10) Theory (10) Tutorialhorizon (10) Kadane - Extended (9) Mathblog (9) Max-Min Flow (9) Maze (9) Median (9) O(32N) (9) Quick Select (9) Stack Overflow (9) System Design (9) Tree - Conversion (9) Use XOR (9) Book Notes (8) Company-Amazon (8) DFS+BFS (8) DP - States (8) Expression (8) Longest Common Subsequence(LCS) (8) One Pass (8) Quadtrees (8) Traversal Once (8) Trie - Suffix (8) 穷竭搜索 (8) Algorithm Problem List (7) All Sub (7) Catalan Number (7) Cycle (7) DP - Cases (7) Facebook Interview (7) Fibonacci Numbers (7) Flood fill (7) Game Nim (7) Graph BFS (7) HackerRank Difficult (7) Hackerearth (7) Inversion (7) Kadane’s Algorithm (7) Manacher (7) Morris Traversal (7) Multiple Data Structures (7) Normalized Key (7) O(XN) (7) Radix Sort (7) Recursion (7) Sampling (7) Suffix Array (7) Tech-Queries (7) Tree - Serialization (7) Tree DP (7) Trie - Bit (7) 蓝桥杯 (7) Algorithm - Brain Teaser (6) BFS - Priority Queue (6) BFS - Unusual (6) Classic Data Structure Impl (6) DP - 2D (6) DP - Monotone Queue (6) DP - Unusual (6) DP-Space Optimization (6) Dutch Flag (6) How To (6) Interviewstreet (6) Knapsack - MultiplePack (6) Local MinMax (6) MST (6) Minimum Spanning Tree (6) Number - Reach (6) Parentheses (6) Pre-Sum (6) Probability (6) Programming Pearls (6) Rabin-Karp (6) Reverse (6) Scan from right (6) Schedule (6) Stream (6) Subset Sum (6) TSP (6) Xpost (6) n00tc0d3r (6) reddit (6) AI (5) Abbreviation (5) Anagram (5) Art Of Programming-July (5) Assumption (5) Bellman Ford (5) Big Data (5) Code - Solid (5) Code Kata (5) Codility-lessons (5) Coding (5) Company - WMware (5) Convex Hull (5) Crazyforcode (5) DFS - Multiple (5) DFS+DP (5) DP - Multi-Dimension (5) DP-Multiple Relation (5) Eulerian Cycle (5) Graph - Unusual (5) Graph Cycle (5) Hash Strategy (5) Immutability (5) Java (5) LogN (5) Manhattan Distance (5) Matrix Chain Multiplication (5) N Queens (5) Pre-Sort: Index (5) Quick Partition (5) Quora (5) Randomized Algorithms (5) Resources (5) Robot (5) SPFA(Shortest Path Faster Algorithm) (5) Shuffle (5) Sieve of Eratosthenes (5) Strongly Connected Components (5) Subarray Sum (5) Sudoku (5) Suffix Tree (5) Swap (5) Threaded (5) Tree - Creation (5) Warshall Floyd (5) Word Search (5) jiuzhang (5)

Popular Posts