Bloomberg

Determine if a string is "cool" - all characters have the same frequency or can become cool by removing exactly one character.

Examples:

• "aaabbb" → true (equal frequencies)
• "aaabbbcccc" → true (remove one 'c' to balance)
• "aaabbbccccdddd" → false
• "aabbcccdddeeee" → false

Implement a card shuffling algorithm for multiple 52-card decks.

Requirements:

• Handle n decks (n * 52 cards total)
• Implement realistic shuffling behavior
• Each card has suit (Hearts, Diamonds, Clubs, Spades) and rank (A, 2-10, J, Q, K)

Function Signature:

struct Card {
    string suit;
    string rank;
};

list<Card> shuffleAllDecks(const list<Card>& all_decks);

Design a system to track and aggregate stock transaction volumes.

Requirements:

• Store and update (stock_name, transaction_count) pairs
• Maintain running totals of transaction volumes
• Provide sorted output by volume (highest to lowest)
• Handle concurrent updates efficiently

Focus on:

1. Data structure choice
2. Update efficiency
3. Sorting performance
4. Memory usage

Print the string inside the deepest set of parentheses.

Example:

• abc(def)g → def
• ab(cde)f(g) → cde, g
• a([bc]d){[{{ef}}]} → ef

A string is valid if all characters of the string appear the same number of times. It is also valid if we can remove just 1 character in the string, and the remaining characters will occur the same number of times. Given a string s, determine if it is valid. If so, return true, otherwise return false.

Examples:

• Input: "abc" → true
• Input: "abcc" → true
• Input: "abccc" → false

Design a data structure that supports the following operations: insert, delete, getRandom. All operations should be done in average O(1) time complexity.

  See: https://leetcode.com/problems/insert-delete-getrandom-o1/

  Follow-up: https://leetcode.com/problems/insert-delete-getrandom-o1-duplicates-allowed/