A detailed review of a Tencent WeChat backend internship interview, including process and technical questions.

First Interview

time: 2020-03-09 16:45:44

Resume Experience

1374. Generate a String With Characters That Have Odd Counts

If n is even, use one a and fill the rest with b;
if n is odd, use all a.

Overall, the difficulty was not high, especially the last two problems, which were not as hard as they should have been.

1370. Increasing Decreasing String

The interview was done by DingTalk phone/video call, and the hand-written coding part was completed through Alibaba’s online platform.

There were two algorithm questions:

1. Implement the data structure for a doubly linked list.

2. twoSum: find the indices of two numbers in an array whose sum equals target.

• HashMap
• Database
  • indexes, optimization, transactions
  • clustered index and non-clustered index
• Concurrent Programming
• Network Programming, RPC
• Algorithm problem:
  • Edit Distance

The algorithm question was to compute Edit Distance (Levenshtein Distance). I had happened to encounter edit distance before while reading Grokking Algorithms, and it can be solved with DP. But this problem was a bit more complex: among many strings, find the string with the smallest distance. It can be understood as “Fuzzy matching”.
The rough statement was:

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莱文斯坦距离，又称 Levenshtein 距离，是编辑距离的一种。指两个字串之间，由一个转成另一个所需的最少编辑操作次数。
允许的编辑操作包括：
插入一个字符
删除一个字符
将一个字符替换成另一个字符
需要你编写一个程序，实现以下功能：
给定一个字符串集合 S 以及一个模板串 P，从 S 中找出与 P 莱文斯坦距离最小的字符串 T，输出 T 以及其对应的编辑距离 D。如果 S 中出现多个满足条件的字符串，则取按字典序排列的第一个。

A contest about speed and being bug-free.

1360. Number of Days Between Two Dates

The problems in this contest were relatively simple. It was another contest of speed and bug-free coding.
After missing contests for half a year, I cannot even get into the top 200 in a smaller biweekly contest anymore. Scary.

1356. Sort Integers by The Number of 1 Bits

Reposted from my blog

2020 is destined to be an unusual year for me, mainly because I am facing the two gates of graduation and job hunting. This is the most important challenge and task I have faced in the past two years. I have prepared for it for a long time, hoping that all the accumulation would finally pay off. Reality, however, did not go as I wished.

Review of 2019

In this contest I finally got AC at the last moment, which was extremely thrilling. Since joining the students in the China region, it has been hard for my weekly contest rank to enter the top 200. For example, this time I dropped from 229 to 306. I have to admit that domestic competition is fierce.

The main reason for the lower ranking was that I spent a lot of time debugging and trying things on the third problem, and almost had no time left to implement the last one. The recent lack of practice has also caused my debug ability and one-pass bug-free ability to drop sharply.