During the job application process for top tech companies, many candidates face a common issue: they get nervous during interviews, their minds go blank, and even though they have practiced similar problems before, they struggle to answer correctly. Amazon, in particular, not only requires candidates to have solid algorithm skills but also demands clear communication, logical reasoning, and composure under pressure. CSOAHELP’s remote interview assistance service is designed to address these challenges, helping you maintain your best performance at critical moments and successfully secure an offer from top-tier companies.

Today, we will analyze a real interview experience of an Amazon SDE candidate, breaking down the technical interview process in detail. We will also demonstrate how CSOAHELP provided precise assistance throughout the interview, helping the candidate navigate the high-pressure environment and pass successfully.

Amazon Interview Question: Data Center Merging

There are different data centers where we can have multiple different types of racks placing which provides compute power. Currently, all data centers (represented as 1) are distributed in a plane separately, but as a developer, you are given the responsibility to check and combine all nearby data centers (directly connected horizontally, vertically, and diagonally) into a single data center so that they become easily accessible to manufacturers without much overhead of checking too many data centers. How many combined data centers will be there after merging?

1 1 0 0 0
0 1 0 0 1
1 0 0 1 1
0 0 0 0 0
1 0 1 1 0

Expected Answer: 4

The candidate had done some preparation before the interview, practicing graph traversal problems on LeetCode. However, when facing an Amazon interviewer, he felt immense pressure. As soon as the interview began, the interviewer presented the problem and asked him to think through a solution quickly.

The interviewer clarified:

• 1 represents a data center, and 0 represents empty land.
• Data centers can be connected horizontally, vertically, and diagonally.
• The goal is to calculate the number of merged data centers.

CSOAHELP’s remote team immediately activated, providing real-time textual prompts to guide the candidate’s thought process.

This problem is essentially a connected components counting problem, which can be solved using Depth-First Search (DFS) or Breadth-First Search (BFS).

• Each time a new data center (1) is found, initiate DFS/BFS traversal to mark all connected regions as visited.
• The number of times DFS/BFS is initiated across the grid represents the final count of merged data centers.

Following CSOAHELP’s prompts, the candidate responded to the interviewer.

“This problem is similar to counting islands. We can use DFS for recursive traversal or BFS with a queue. Each time we find a data center, we mark all connected 1s as visited before continuing.”

The interviewer nodded in approval and asked him to write the code.

However, the interviewer didn’t stop there and continued questioning: “What happens when the grid size increases significantly, say 1000x1000 or even larger? Wouldn’t a recursive DFS cause a stack overflow? How can you optimize this?”

The candidate hesitated for a moment. CSOAHELP quickly provided a tip: “You can use an iterative DFS or BFS to avoid stack overflow due to deep recursion.”

The candidate immediately adjusted his approach. “Yes, if the grid size increases significantly, a recursive DFS might cause a stack overflow. We can switch to an iterative DFS or use BFS with a queue, which prevents deep recursion issues.”

The interviewer was pleased with the response. “Now, what if the grid changes dynamically, where data centers are added or removed over time? How would you make your algorithm more efficient?”

CSOAHELP quickly assisted: “Consider using Union-Find (Disjoint Set) to efficiently merge data centers.”

The candidate continued, “If the grid is dynamic, we can use the Union-Find data structure to efficiently maintain the connectivity of data centers. This allows us to add and remove data centers in near-constant time.”

The interviewer smiled. “Great. Now, please write your code.”

The candidate began coding, while CSOAHELP’s team monitored remotely and provided optimization suggestions when necessary.

def count_data_centers(grid):
    rows, cols = len(grid), len(grid[0])
    directions = [(-1,-1), (-1,0), (-1,1), (0,-1), (0,1), (1,-1), (1,0), (1,1)]
    
    def dfs(r, c):
        grid[r][c] = 0  # Mark visited
        for dr, dc in directions:
            nr, nc = r + dr, c + dc
            if 0 <= nr < rows and 0 <= nc < cols and grid[nr][nc] == 1:
                dfs(nr, nc)
    
    count = 0
    for r in range(rows):
        for c in range(cols):
            if grid[r][c] == 1:
                count += 1
                dfs(r, c)
    return count

The interviewer ran the code and obtained the correct answer, 4, confirming that the implementation was correct.

As part of further optimizations, the interviewer continued: “What if the grid wraps around, meaning the rightmost 1 can connect to the leftmost 1? How would you modify your code?”

CSOAHELP provided a quick response, and the candidate answered smoothly.

“We can use modular arithmetic: nr = (r + dr) % rows, nc = (c + dc) % cols to simulate a toroidal (wraparound) grid.”

The interviewer was impressed by the optimized approach and praised the candidate’s performance.

This candidate ultimately passed the Amazon technical interview and moved on to the next round.

Without CSOAHELP’s real-time assistance, he might have struggled to recall key concepts under pressure, omitted crucial edge cases in his implementation, or made errors in the coding process, potentially losing this valuable opportunity.

• Remote real-time assistance ensures you don’t get stuck during the interview.
• Precise problem breakdown helps you structure your answers effectively and avoid common pitfalls.
• Optimized communication ensures your solutions are clearly articulated, leaving a positive impression on the interviewer.

If you’re preparing for a big tech interview and don’t want to risk losing out due to stress or unclear thinking, CSOAHELP is your most reliable interview support partner!

经过csoahelp的面试辅助，候选人获取了良好的面试表现。如果您需要面试辅助或面试代面服务，帮助您进入梦想中的大厂，请随时联系我。

If you need more interview support or interview proxy practice, feel free to contact us. We offer comprehensive interview support services to help you successfully land a job at your dream company.