Bloomberg·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

Jun 2026

Summary

Bloomberg follow-up coding round, one problem but they kept pushing on complexity until you got to a proper O(n) solution. Felt like a reasonable problem until the interviewer started asking for a single-pass approach and I had to think harder than expected.

Questions Asked (1)

Given a string, you must remove exactly one character (no skipping even if already balanced). After removal, check whether all remaining characters appear with equal frequency. Return true or false.

Algorithms & Data Structures

Author's notes

My first instinct was to just count frequencies, try removing each character, and recheck.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

First, compute the frequency of each character in the string. Then, for each character, simulate removing one occurrence and check if the remaining frequencies are all equal. To optimize, identify the distinct frequency values and test only the characters that could lead to equality.

Pro tip: Clarify edge cases upfront: strings of length 1 or 2, and whether removal must leave at least one character. Also, mention that you can avoid O(n^2) by analyzing frequency patterns rather than brute-force trying every removal.

1. Understand the problem and edge cases

Restate the problem: remove exactly one character, then check if all remaining characters have the same frequency. Discuss edge cases like empty string, single character, and strings where removal leaves no characters.

2. Compute character frequencies

Iterate through the string and build a frequency map (e.g., using a hash map or array). This gives the count of each character.

3. Analyze frequency distribution

Examine the distinct frequency values. If all frequencies are already equal, removing any character will break equality unless the string length is 1. Otherwise, identify the frequencies that differ and determine which character removal could balance them.

4. Simulate removal for candidate characters

For each character that could potentially be the one to remove (based on frequency analysis), decrement its count and check if all remaining non-zero frequencies are equal. Return true if any removal works.

5. Optimize and verify

Instead of checking every character, use the frequency distribution to limit candidates. For example, if there are two distinct frequencies, only characters with the higher frequency (if it appears once) or the lower frequency (if it appears once) need testing. Verify with examples.

Key Points to Mention

Use a hash map to count character frequencies efficiently.
Edge cases: empty string, single character, all characters same, removal leading to empty string.
Time complexity: O(n) with frequency analysis, O(n^2) with naive simulation.
Space complexity: O(1) if using fixed-size array for ASCII, O(k) for hash map.
Condition for equality: all non-zero frequencies after removal must be the same.
Optimization: only test characters whose frequency is a candidate for removal based on the frequency distribution.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.