themichaelyang

def unique_paths(m, n)
  grid = Array.new(m)

  m.times.with_index do |y|
    grid[y] = Array.new(n)
    grid[y][0] = 1

    n.times.with_index do |x|
      from_left = if x - 1 >= 0 then grid[y][x - 1] else 0 end
      from_above = if y - 1 >= 0 then grid[y - 1][x] else 0 end

themichaelyang

def rob(nums)
  rob_impl(nums, 0)
end

# https://nithinbekal.com/posts/ruby-memoization/
# https://stackoverflow.com/questions/35595047/how-to-generically-memoize-any-function-in-ruby
# We could use a Class instance to hold the memory
def memoize(method_name)
  memory = {}
  original = method(method_name)

themichaelyang

# For some reason, only iterative DP passes Leetcode

def coin_change(coins, amount)
  result = coin_change_iterative(coins, amount)
  if result.infinite?
    -1
  else
    result
  end
end

themichaelyang

class NumMatrix 
  # (0, 0) is the top left
  def initialize(matrix)
    @corner_areas = matrix
    @corner_areas.each.with_index do |row, y|
      row.each.with_index do |value, x|
        upper_sum = positive_dig(@corner_areas, y - 1, x)
        left_sum = positive_dig(@corner_areas, y, x - 1)

        @corner_areas[y][x] = value + upper_sum + left_sum - positive_dig(@corner_areas, y - 1, x - 1)

themichaelyang

# Here is my solution, ignoring the sparse optimization, so we iterate over k. Originally, I wanted to only keep track
# of the locations with fruit.
def max_total_fruits(fruits, start_pos, k)
  steps = []

  fruits.each do |pos, amount|
    steps[pos] = amount
  end

  right_sum = 0

themichaelyang

def max_score(card_points, k)
  left_sums = cumulative_sum(card_points[0...k]).prepend(0)
  right_sums = cumulative_sum(card_points[-k..-1].reverse_each).reverse.append(0)

  left_sums.zip(right_sums).map(&:sum).max
end

def cumulative_sum(iter)
  sum = 0
  iter.map {|x| sum += x}

themichaelyang

class NumArray
  def initialize(nums)
    sum = 0
    @prefix_sums = nums.map do |x|
      sum += x
    end
    @prefix_sums.prepend(0)
  end

  def sum_range(left, right)

themichaelyang

@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);
/* Adapted from: https://www.reddit.com/r/FirefoxCSS/comments/bm77hx/modern_firefox/ */

/* the little line under the title bar separating it from content */
#navigator-toolbox::after {
  height: 0px !important;
}

#personal-bookmarks #PlacesToolbarItems {
  -moz-box-pack: center;

themichaelyang

# MIT OCW 6.0001
# PSET 1C
# SOLUTION

# salary
starting_annual_salary = int(input("Starting salary? "))
# starting_annual_salary = 10000
semi_annual_raise = 0.07

# investments

themichaelyang

history | sed -E 's/(^( )+[0-9]+  [0-9\:T\-]+)  //'