aniruddha84

# Problem: https://leetcode.com/problems/letter-combinations-of-a-phone-number/
# Given a digit string, return all possible letter combinations that the number could represent.
# Input:Digit string "23"
# Output: ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"].


@look_up = {
    "2" => "abc",
    "3" => "def",
    "4" => "ghi",

aniruddha84

def number_map
  {
      "0" => 0,
      "1" => 1,
      "2" => 2,
      "3" => 3,
      "4" => 4,
      "5" => 5,
      "6" => 6,
      "7" => 7,

aniruddha84

def stack_sort(stack)
    result = []

    until stack.empty?
      t = stack.pop
      while !result.empty? && result.last > t
        stack.push result.pop
      end
      result.push t
    end

aniruddha84

def next_successor(bnode)
    if bnode.right
      curr = bnode.right
      until curr.left.nil?
        curr = curr.left
      end
      curr
    else
      curr = bnode
      prev = bnode.parent

aniruddha84

def find_lca(val1, val2, root)
    stack = []
    stack.push [root, []]
    ancestor_list_val1 = []
    ancestor_list_val2 = []
    until stack.empty?
      t = stack.pop
      if t[0].data == val1
        ancestor_list_val1 = t[1]
      elsif t[0].data == val2

aniruddha84

  # Given a start string, end string and a set of strings, find if there exists a path
  # between the start string and end string via the set of strings.
  # start: "cog" end: "bad"
  # set: ["bag", "cag", "cat", "fag", "con", "rat", "sat", "fog"]
  # one of the paths: "cog" -> "fog" -> "fag" -> "bag" -> "bad"
  def path_exists?(start_str, end_str, arr)
    return true if string_diff(start_str, end_str) == 1
    arr.each do |s|
      if string_diff(s, start_str) == 1
        arr.delete(s)

aniruddha84

# Given an input array  and target sum, find all possible ways the elements of the array can be added upto get target
# sub_set_sum([10, 7, 5, 18, 12, 20, 15], 35) => [
#     [10, 7, 18],
#     [10, 5, 20]
#     [5, 18, 12],
#     [20, 15]
#   ]
require 'set'
def subset_sum(arr, sum, curr_arr = [], result = Set.new)
    return if arr.nil?

aniruddha84

def longest_nonrepeating_substring(str)
    max_len = 0
    look_up = {}
    len = 0
    last_repeating_index = 0 # indicates beginning of unique string
    (0...str.size).each do |index|
      if (p = look_up[str[index]]) # repeat char found at index
        if p > last_repeating_index 
          len = index - p
          last_repeating_index = p

aniruddha84

# @param {Integer[][]} board
# @return {Void} Do not return anything, modify board in-place instead.
def game_of_life(board)
    m = board.size
    n = board[0].size
    meta_data = {}
    (0...m).each do |row|
      (0...n).each do |col|
        living_neighbours = live_neighbours(board, row, col)
        # meta-data format -> [row:col] => [old_value, num_of_live_neighbours]

aniruddha84

// https://leetcode.com/problems/remove-duplicates-from-sorted-array/description/
public void removeDuplicates(int[] arr) {
   if (arr.length <= 1) return arr.length;
   int p1 = 1;
   for(int i = 1; i < arr.length; i++) {
     if (arr[i] != arr[i-1]) {
       arr[p1] = arr[i];
       p1 += 1;
     }
   }