I recently finished a round of brushing Bytedance Online Assessment, in CodeSignal The platform completed a full set of 4 questions in approximately 70 minutes. The difficulty of the questions is not particularly high, but the test logic, observation ability and coding details are completely typical of the question bank style, and Visa/Capital One/HRT/SIG Very similar. In summary, it is entirely possible to complete it within 30 minutes, but if you are careless or do not grasp the characteristics of the question, it is easy to get stuck on the boundary conditions. Below I share my feelings and solutions to each question.
Matrix Completion
Problem Description:
The given matrix mat contains only one 4×4 square (based on column segments), so we just find the missing value in it (in the example, it is 11), and replace the “?” with this value.
Analysis and ideas:
- The matrix width is a multiple of 4, and the numbers in each 4×4 square are unique
- Turn up
"?"The 4×4 block in which - Collect the numbers that have appeared, by
1..16Difference from existing numbers to get missing values - Will
"?"Replace
Tips:
- The string is first converted to an integer to facilitate set operations.
- Even if the number of columns is large, it remains efficient to process only squares
Molecular Bond Balancing
Problem Description:
You are a chemist working in a laboratory that studies molecular compounds. You have two arrays representing the atomic weights of elements in two different compounds: x represents the primary elements and y represents the secondary elements. Your research has shown that when two compounds have the same “balance factor” (calculated as the difference between primary and secondary atomic weights), they can potentially form stable molecular bonds. Count the total number of valid molecular pairings (i, j) where i ≤ j and the balance factors are equal: x[i] – y[j] = x[j] – y[i].
Analysis and ideas:
- The core formula can be simplified to
X[i] + y[i] = x[j] + y[j] - Iterate through the array and calculate the sum of each element
X[i]+y[i] - Use a hash table to count the number of occurrences of each sum
- For a value with frequency k, the number of combinations is
K*(k-1)/2 - Accumulate to get the total number of pairs
Tips:
- Avoid brute force enumeration
(i,j), complexity O(n²) will time out - Hash statistics reduce complexity to O(n)
Consonant Substitution Cipher
Problem Description:
You’re implementing a simple substitution cipher that only affects consonant characters in a memo. This cipher works by shifting every k-th consonant to the following consonant in the alphabet, while leaving vowels and other characters unchanged.
Analysis and ideas:
- Iterate over the string and maintain a consonant counter
- Whenever the kth consonant is encountered, replace it with the next consonant
- Note the case and z -> b loop
- Other characters remain unchanged
Tips:
- It is recommended to predefine the consonant order table to make search and replacement more convenient.
- Consonant counting must be accurate. The easy points to make mistakes are wrap-around and capitalization.
Monotonic Triplets
Problem Description :
You are given an array of integers arr. Determine whether each sequence of three elements in the array (arr[i], arr[i+1], arr[i+2]) are monotonic.
Analysis and ideas:
- Sliding window takes every three consecutive elements
- Judgment is strictly incremental
Arr[i] < arr[i+1] < arr[i+2]Or strictly decreasingArr[i] > arr[i+1] > arr[i+2] - Returns 1 if the condition is met, otherwise 0
Tips:
- Note the equal sign, it must be strictly monotonic
- Complexity O(n) is completely sufficient
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