This is the December 20 article for Eureka Advent Calendar 2021.



Hi, I’m nari/wapper from SRE team at eureka, Match Group.👋

These days I work on data lifecycle privacy project/data platform migration/moderation ML systems and so on…(Wondering if I’m Site Reliability Engineer engineer)

Let’s move on to the…


Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

An input string is valid if:

  1. Open brackets must be closed by the same type of brackets.
  2. Open brackets must be closed in the correct order.

Note that an…


Write a function to find the longest common prefix string amongst an array of strings.

If there is no common prefix, return an empty string "".

Example 1:

Input: ["flower","flow","flight"]
Output: "fl"

Example 2:

Input: ["dog","racecar","car"]
Output: ""
Explanation: There is no common prefix among the input strings.


All given inputs are in lowercase letters a-z.


/*Go Approach 1: Horizontal scanning*/
/*Time complexity : O(S), where S is the sum of all characters in all strings.*/
/*Space complexity : O(1). We only used constant extra space. */
func longestCommonPrefix(strs []string) string {
if len(strs) == 0 {
return ""
// Assume prefix
prefix := strs[0]
for i := 1; i < len(strs); i++ {
for !strings.HasPrefix(strs[i], prefix) {
prefix = prefix[0:len(prefix)-1]
if len(prefix) == 0 {
return ""
return prefix


Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.

Example 1:

Input: 121
Output: true

Example 2:

Input: -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. …


Given a 32-bit signed integer, reverse digits of an integer.

Example 1:

Input: 123
Output: 321

Example 2:

Input: -123
Output: -321

Example 3:

Input: 120
Output: 21

Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231, 231 − 1]…


Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.


Given nums = [2, 7, 11, 15], target =…


Site Reliablity Engineer in Tokyo. SRE/devops/Go/AWS/Terraform/Kubernetes/Docker

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store