Published in AWS in Plain English·PinnedMember-onlyHow to Clean Up DynamoDB Records Through Time-to-Live (TTL)Archive obsolete table records into the S3 bucket — One way you can remove any DynamoDB table record is via hard delete operations such as DeleteItem or BatchWriteItem with DeleteRequest. These delete operations have to be triggered by administrators or any user who has delete privilege. On top of that, these deletes are real-time. Nobody can access any record…AWS3 min read
Published in AWS in Plain English·PinnedMember-onlyCloudWatch Log Records— Send Critical Ones to a Slack ChannelSolve it by Lambda attached to an SNS topic — You have a custom logger in place for a lambda function in your AWS account and this logger writes JSON records to CloudWatch through that lambda log group. Now out of all these log records being dumped in the log group, you want to send all logs that contain the…AWS3 min read
Published in AWS in Plain English·17 hours agoMember-onlyAWS SAM template: Globals sectionHow it helped to eliminate confusions in code — In my work, we use AWS SAM template to define the serverless architecture in DEV, QA and PROD AWS accounts/environments. The template file in this architecture contains the definition of all lambda functions, lambda permissions, apis, event source mappings etc. Now there were some common environment variables being used across…Aws Sam2 min read
Published in coding interview preparation·Sep 23Member-onlyLeetcode: Reverse Odd Levels of Binary TreeA practice problem for a level-order traversal of a tree — Given the root of a perfect binary tree, reverse the node values at each odd level of the tree. For example, suppose the node values at level 3 are [2,1,3,4,7,11,29,18], then it should become [18,29,11,7,4,3,1,2]. Return the root of the reversed tree. A binary tree is perfect if all parent…Binary Tree2 min read
Published in coding interview preparation·Sep 9Member-onlyLeetcode: Longest Nice SubarrayA bitmask problem — You are given an array nums consisting of positive integers. We call a subarray of nums nice if the bitwise AND of every pair of elements that are in different positions in the subarray is equal to 0. Return the length of the longest nice subarray. A subarray is a…Bitmasking2 min read
Published in coding interview preparation·Aug 21Member-onlyLeetcode: Amount of Time for Binary Tree to Be InfectedA binary tree/graph problem — You are given the root of a binary tree with unique values, and an integer start. At minute 0, an infection starts from the node with value start. Each minute, a node becomes infected if: The node is currently uninfected. The node is adjacent to an infected node. Return the…Python2 min read
Published in AWS in Plain English·Aug 15Member-onlyA Way to Build Custom Widget on CloudWatch DashboardHave a lambda function to process data and create the plot for you — In this article, I will guide you on adding a custom widget on the CloudWatch dashboard using a lambda function and Matplotlib. The idea is that the CloudWatch dashboard allows to add custom widget which can load widget plot directly from a lambda function. All you have to do is…Matplotlib2 min read
Published in coding interview preparation·Aug 14Member-onlyLeetcode: a bitmask dp problemConstruct Smallest Number From DI String — You are given a 0-indexed string pattern of length n consisting of the characters 'I' meaning increasing and 'D' meaning decreasing. A 0-indexed string num of length n + 1 is created using the following conditions: num consists of the digits '1' to '9', where each digit is used at…Leetcode2 min read
Published in coding interview preparation·Jul 31Member-onlyA Leetcode hard problem on graphLongest Cycle in a Graph — You are given a directed graph of n nodes numbered from 0 to n - 1, where each node has at most one outgoing edge. The graph is represented with a given 0-indexed array edges of size n, indicating that there is a directed edge from node i to node…DFS3 min read
Published in coding interview preparation·Jul 31Member-onlyLeetcode: Find Closest Node to Given Two NodesA graph problem — You are given a directed graph of n nodes numbered from 0 to n - 1, where each node has at most one outgoing edge. The graph is represented with a given 0-indexed array edges of size n, indicating that there is a directed edge from node i to node…Bfs3 min read
