This time Meta OA is on CodeSignal, with 4 programming questions in 70 minutes, and the pace is very tight. To be honest, this set of questions requires a high level of algorithm proficiency. If you haven’t done much of Amazon/Google/TikTok/Meta type of questions, it’s easy to crash in the last two questions. I am relatively familiar with the routines of these OA companies. This game was a steady and steady attack + proper time control, and in the end it was all AC. Let’s break down all 4 questions and explain them clearly.
T1｜Basic simulation questions
Most of these questions are pure simulation or rules questions. The logic itself is not difficult, but there are many details, and it is very easy for "people who have not read the questions clearly" to get stuck. Common test points include whether conditional branches are completely covered, whether boundary cases (empty, minimum values, maximum values) are handled, and whether the problem is implemented strictly according to the meaning of the question rather than written based on feeling. The rule of thumb is not to write it in seconds at a glance. First, go through the logic according to the example and then start coding. This can ensure that it is done in one go and avoid being dug in by yourself later.
T2｜Statistics + Left-right relationship judgment
Question meaning
For each element x in the array, we need to count the number of elements in the array that are strictly greater than x, and further distinguish whether these elements are on the left or right of x. Determine the location of x based on the statistical results: the number on the left is greater than the right → put it in the "left area"; the number on the right is greater than the left → put it in the "right area"; equal → put it in the "middle".
Core point
- It must be strictly greater, not greater than or equal to.
- Left and right are left and right in the subscript sense and cannot be confused.
Solution ideas
For each element, directly traverse the entire array to count the number of elements that are strictly greater than it, then distinguish the left and right according to the subscript, and finally classify the output according to three situations. The time complexity is O(n²), the data size of CodeSignal allows it, and no additional optimization is required. The essence of this question is to examine whether you can steadily translate rules into code.
T3｜String exchange → Union search/graph connected components
Question meaning
Given a string S And two equal-length arrays Arr,Brr, you can select a subscript for each operation I,exchange S[arr[i]] And S[brr[i]]. There is no limit to the number of operations, and the goal is to obtain the smallest string in lexicographic order.
Key understanding
The unlimited number of exchanges means that "the characters that can be exchanged can be rearranged at will." As long as it is possible to pass between two locations (arr[i], brr[i]) Or multiple exchange chains are connected together, they belong to the same connected component, and the characters in this component can be rearranged arbitrarily. This is the watershed of this question and the core of the correct solution.
Solution ideas
Treat each subscript of the string as a node, and use union search (or DFS) to (arr[i], brr[i]) Connect them and find all connected components. For each component: take out the characters at these positions, sort them (in ascending order), and put them back in index order. The final result is the string with the smallest global lexicographic order. This question appears very frequently in Meta/Google/Amazon OA. The essence of the question is whether "exchangeable" can be accurately abstracted into "rearrangeable".
T4｜Multi-task Prompt / command design questions
Such questions are usually very long and contain multiple subtasks and constraints. The essence is not NLP, but rule execution and state management. Common pitfalls include missing a subtask, the output format is not completely consistent, or instructions are not executed in order. The correct approach is to first dismantle each sub-task, clarify the input and output mapping relationship of each step, ensure a clear code structure, and avoid writing a bunch of if-else. This type of question is very typical in Meta OA. The focus of the test is reading patience, instruction execution ability and engineering thinking, rather than algorithmic skills.
Programhelp summarizes one sentence
The real difficulty of Meta OA is not a certain question, but:
- 70 minutes 4 questions pacing control
- Are you familiar with Meta frequently tested models?
- Can you "not write useless code" under pressure?
If you have done it usually Amazon/Google/TikTok/Meta In this set of question types, you will find that the routines are highly reusable;
But if you have never been exposed to it and write CodeSignal’s Meta OA for the first time, there is a high probability that time will take it away directly.
This is why we always emphasize:
OA is not a question of how many questions you have to answer, but a question of whether you are familiar with the logic of the questions.
OA & practical support for written examinations of major manufacturers
If you are preparing for OA or written examinations from major North American companies such as Meta/Amazon/Google/TikTok, but encounter a large number of questions, tight time, and unfamiliarity with platform operation, or you have algorithm ideas but cannot keep up with the implementation speed, Programhelp provides mature and stable OA practical support services . Assistance is handled in real time by people with engineering backgrounds who have long been involved in OA from major manufacturers. Based on the question-setting habits of different companies and platforms, we can help you cope with the challenges of time pressure, platform limitations, and extremely low fault tolerance rates. Take Meta's 70-minute, 4-question high-paced CodeSignal OA as an example. Having someone to help you clarify your thoughts and stabilize your hand speed at key nodes is often the difference between full AC and being eliminated by the system.
