Software Engineer · Phone Screen · Coding

Uber — Software Engineer ❌ Failed

Level: Mid-Level

Round: Phone Screen · Type: Coding · Difficulty: 6/10 · Duration: 60 min · Interviewer: Unfriendly

Topics: Trie, Backtracking

Location: San Francisco, CA

Interview date: 2025-11-01

Got offer: False

Summary

I had a technical phone interview. The question involved using a Trie, but I couldn't remember how to implement it. I asked if I could use backtracking instead. The interviewer agreed. After I finished the backtracking solution, the interviewer asked me to explain how a Trie would work.

Details

The coding question I received involved using a Trie data structure.

` // Trie Implementation (Example) class TrieNode: def init(self): self.children = {} self.is_word = False

def insert(self, word):
    node = self
    for char in word:
        if char not in node.children:
            node.children[char] = TrieNode()
        node = node.children[char]
    node.is_word = True

`

My Approach:

1. Since I couldn't recall the Trie implementation details, I proposed using backtracking.
2. I implemented a backtracking solution, which the interviewer accepted.
3. The interviewer then asked me to explain how a Trie would solve the problem.

Key Takeaways:

• Be prepared to discuss alternative solutions and their trade-offs.
• If you can't implement the optimal solution, propose an alternative and explain its complexities.
• It's essential to have a solid understanding of fundamental data structures like Tries.

LeetCode similar: LeetCode 212