Chime

Implement solutions for stock trading problems with varying constraints.

Part 1: Single Transaction

function maxProfit(prices: number[]): number

Example: prices = [7,1,5,3,6,4] → Output: 5 Buy on day 2 (price = 1) and sell on day 5 (price = 6)

Part 2: Two Transactions

function maxProfitTwo(prices: number[]): number

Example: prices = [3,3,5,0,0,3,1,4] → Output: 6 Buy at 0, sell at 3, then buy at 1, sell at 4

Part 3: K Transactions

function maxProfitK(k: number, prices: number[]): number

Example: k = 2, prices = [2,4,1] → Output: 2

Implement browser tab navigation with back and forward functionality.

Class Methods:

class BrowserTabs {
    visit(url: string): void
    back(steps: number): string
    forward(steps: number): string
}

Example: visit("google.com") visit("facebook.com") visit("youtube.com") back(1) → "facebook.com" forward(1) → "youtube.com"

Implementation:

• Use two stacks for history
• Handle edge cases
• O(1) operations

Design a system to manage food ratings and queries.

Requirements:

1. Rate foods (1-5 stars)
2. Get highest rated foods
3. Get lowest rated foods
4. Calculate average ratings

Example Usage:

rateFood("Pizza", 5)
rateFood("Burger", 3)
getHighestRated() → ["Pizza"]
getAverageRating() → 4.0

Implementation:

• Track ratings per food
• Maintain sorted order
• Handle updates efficiently

Given a range [1-n] and a string of numbers, find the missing number.

function findMissing(n: number, str: string): number

Examples:
Input: n = 5, str = "1234"
Output: 5

Input: n = 13, str = "1310923..."
Output: Missing number in range [1-13]

Find highest visible building looking right for each building.

function findVisibleBuildings(heights: number[]): number[]

Requirements:
- Taller buildings block view of shorter ones
- Return -1 if no taller building visible
- Consider line of sight mechanics

Find valid dictionary words from phone number combinations.

function letterCombinations(digits: string, dict: Set<string>): string[]

Similar to LeetCode 17 but:
- Only return combinations in dictionary
- Handle invalid combinations
- Optimize dictionary lookups

Find length of longest increasing path in matrix.

function longestIncreasingPath(matrix: number[][]): number

Constraints:
- 1 <= m,n <= 200
- 0 <= matrix[i][j] <= 2^31 - 1
- Only move up/down/left/right
- No diagonal movement
- No boundary wrapping

Example:
Input: [
  [9,9,4],
  [6,6,8],
  [2,1,1]
]
Output: 4 (path: 1→2→6→9)

Select k engineers to maximize team performance.

function maxPerformance(
  n: number,
  speed: number[],
  efficiency: number[],
  k: number
): number

Performance = sum(speeds) * min(efficiencies)

Example:
Input: 
n = 6
speed = [2,10,3,1,5,8]
efficiency = [5,4,3,9,7,2]
k = 2
Output: 60 (engineers 2 and 5)

Constraints:
- 1 <= k <= n <= 10^5
- 1 <= speed[i] <= 10^5
- 1 <= efficiency[i] <= 10^8

Find mine with largest explosion radius impact.

interface Mine {
  x: number;
  y: number;
  radius: number;
}

function findMostDestructive(mines: Mine[]): Mine

Example:
Input: [
  {x: -3, y: 3, radius: 3},
  {x: -1, y: 2, radius: 3},
  ...
]
Output: {x: -2, y: -2, radius: 3.5}

Count connected land cells in binary grid.

function numIslands(grid: string[][]): number

Example:
Input: [
  ["1","1","0","0","0"],
  ["1","1","0","0","0"],
  ["0","0","1","0","0"],
  ["0","0","0","1","1"]
]
Output: 3

Constraints:
- 1 <= m,n <= 300
- grid[i][j] is '0' or '1'

Find max unique candy flavors after sharing k consecutive candies.

function maxUniqueFlavors(
  candies: number[],
  k: number
): number

Example:
Input: candies = [1,2,2,3,4,3], k = 3
Output: 3

Constraints:
- 1 <= candies.length <= 10^5
- 1 <= candies[i] <= 10^5
- 0 <= k <= candies.length

Calculate how many times a sentence fits on screen.

function wordsTyping(
  sentence: string[],
  rows: number,
  cols: number
): number

Requirements:
- Words can't be split across lines
- Skip to next line if word doesn't fit
- Optimize for large screens

Generate n x n matrix with numbers 1 to n^2 in spiral order.

function generateMatrix(n: number): number[][]

Example:
Input: n = 3
Output: [
  [1,2,3],
  [8,9,4],
  [7,6,5]
]

Constraints:
- 1 <= n <= 20

Find maximum loot without robbing adjacent houses.

function rob(nums: number[]): number

Example:
Input: [5,5,10,100,10,5]
Output: 110
Explanation: Rob 5 + 100 + 5 = 110

Constraints:
- Can't rob adjacent houses
- Maximize total amount
- Handle various array sizes

Validate partially filled 9x9 Sudoku board.

function isValidSudoku(board: string[][]): boolean

Rules:
1. Each row: digits 1-9 without repetition
2. Each column: digits 1-9 without repetition
3. Each 3x3 sub-box: digits 1-9 without repetition

Note: Only validate filled cells

Find if word exists in grid, allowing cell revisits.

function exist(
  board: string[][],
  word: string
): boolean

Requirements:
- Adjacent cells only (horizontal/vertical)
- Can reuse same cell
- Return true if word exists
- Handle all edge cases